New Publications are available for Sonic and ultrasonic applications
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New Publications are available now online for this publication.
Please follow the links to view the publication.Development of a multi-purpose wireless network for the structural health monitoring of a suspension bridge
http://dl-live.theiet.org/content/conferences/10.1049/cp.2012.0593
Wi-Health is an EC sponsored project to help a consortium of SMEs develop a unique combined AE (Acoustic Emission) and LRU (Long Range Ultrasonic) structural health monitoring system for a bridge. The aims of the project, which was started in October 2011, are described, along with some of the challenges which have to be overcome. (5 pages)Using acoustic images for human identification
http://dl-live.theiet.org/content/conferences/10.1049/ic.2011.0161
An acoustic electronic scanning array is developed to acquire acoustic images from a person. On the basis of pulse- echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two uniform linear arrays with 15 λ/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Work frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and of sensors. Finally, for a case of study with 6 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. According to the obtained results, this system will be able to be used for biometric applications. (5 pages)Decreasing the influence of dispersive wave modes in long-range ultrasonic rail testing using wavelets
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0617
The sensitivity and the resolution of long-range ultrasonic testing (LRUT) are significantly limited by the presence of dispersive wave modes, commonly inherent to the acquired ultrasonic signals. This paper presents a signal processing technique based on the discrete wavelet transform (DWT) for reducing the effect of dispersive wave modes in LRUT of rails. A comparative study of different type of wavelet, thresholding procedures and threshold selection rules is presented. The proposed concept has been evaluated in the presence of high level of additive dispersive waveform at signal to noise ratio (SNR) from -20dB to 20dB. The results show that the effect of dispersion can be reduced in great extent even in the case of extremely high SNR level. (6 pages)Phased array inspection of aluminothermic rail welds. The automated solution - a fast convenient means of inspecting rail joints arrives
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0610
There are millions of aluminothermic welds made each year to join rail in Europe's rail network and millions are already in-service. Occasionally flaws develop during and shortly after welding that can lead to early failure and this can cause disruption to train services and costs to both the train operating companies and the maintenance operators. Although radiographic inspection is sometimes carried out, this is not very common, and the conventional ultrasonic standard requires many probes and scans because of the complex geometry. Since the welds are made by a casting process, these can be more difficult to inspect than joints made by other welding processes. Hence, the RAILECT project was conceived to provide a convenient means of inspecting the joints using a multiple phased array ultrasonic system. (5 pages)SpaceAnnotator: a high precision location based asset management system in indoor environment
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0748
Asset management is urgently needed in supply chain which requires to solve two basic problems 1) what assets do we have; and 2) where they are? Existing methods exploit barcode and RFID technologies to retrieve the information and quantity of assets. However, the location of asset is still hard to obtain for the lack of suitable location technologies. In this paper, a high precision location based asset management system named SpaceAnnotator is proposed. SpaceAnnotator is implemented based on TOA positioning method using Ultrasound and RF signals. Leveraging the centimeter level positioning accuracy provided by the positioning system, SpaceAnnotator maps the IDs of objects to their locations. Based on the location information, location based service (LBS) in provided for asset management. Compared with conventional location based asset management system, SpaceAnnotator works well even in managing small volume objects for its high accuracy.The application of long range ultrasonic testing (LRUT) for examination of hard to access areas on railway tracks
http://dl-live.theiet.org/content/conferences/10.1049/cp.2011.0618
Following a number of severe accidents caused by rail breaks, there has been a significant improvement in NDT methods for the detection of rail head defects. However, current NDL methods are limited in their ability to detect defects in the rail foot, especially in the side edges away from the region directly below the web. Long Range Ultrasonic Lesting (LRUT) is proposed as a complimentary inspection technique to examine the foot of rails, especially in track regions where corrosion and associated fatigue cracking is likely, such as at level crossings. The focus of this study is to demonstrate the ability of using LRUT to examine inaccessible railway tracks areas for corrosion and fatigue cracking. In this paper, the properties of guided waves in the three different parts of the rail section (head, web and foot) are examined and their capability to detect defects in each part is explored. The purpose of this work is to develop suitable arrays of transducers able to generate selected guided wave modes in rails which will allow a reliable long range inspection of the rail. This investigation has being carried out using Finite Element Analysis (FEA) as well as experimental trials. The findings have shown that ultrasonic guided waves can propagate in rails with the ability to detect common type of defects. The emphasis of the work is on the foot since currently applied NDT methods are less effective in this region. Nevertheless, work has been also carried out in the web and the head in order to develop a cost effective and global inspection solution. (7 pages)Research on image filtering method to combine mathematics morphology with adaptive median filter
http://dl-live.theiet.org/content/conferences/10.1049/cp.2010.1152
As a imaging technology of no-traditional lamp-house irradiation ,ultrasound medical imaging with its many advantages, such as no harm to the human body, real-time, cheap and easy to use, is widely used in clinic. But the ultrasonic imaging speckle noise make it difficulties to distinguish between normal tissue and pathological tissue. According to the character of noise in the medical ultrasonic image , an new method of the medical ultrasonic imaging filter based on mathematics morphology and adaptive filtering is proposed after analysis of speckle noise and general filter, and an experiment is made to validate. The experimental method is as follows : Firstly the Rayleigh noise is imposed on the original image , and then the median filter and the adaptive median filter are used on the contaminated image. Secondly the morphological filter is used to improve image quality and enhance the contrast , after the adaptive median filter is used on the image, to retain more necessary details. Finally the three noise filtering methods are compared from the images denoise and evaluation . And the results indicate that the new method is superior to other ones.Study on the acoustic system of the ultrasonic micro milling machine
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1416
In order to machine the small shape of hard and brittle materials, Ultrasonic micro-milling was considered an effective method, especially for the materials' precision machining and ultra-precision machining. Aiming the requirement of micro-machine that it should have small size and high precision, the acoustic system was designed. Modal analysis was used for the designed acoustic system with the soft of finite element analysis. A batch of acoustic systems were made for the experimental testing. The testing result reported that the parameters of the acoustic system for the ultrasonic micro-milling achieve the requirement. (6 pages)Estimation of tissue elasticity by image processing of simulated B-mode ultrasound images
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1682
Elastography and strain imaging often use ultrasound to measure mechanical properties of soft tissues. These techniques generally examine radiofrequency signals from an ultrasound scanner. This study investigates the feasibility of strain estimation directly from an ultrasound B-mode image, using segmentation and shape analysis. Several thousand computer generated tissue mimicking phantoms with stiff inclusions were produced and analysed, evaluating the change in shape when the phantom is subjected to 1-D compression in order to estimate strain. The resulting stiffness measurements are accurate to within 8% of the actual values. (6 pages)Kinematics analysis and experimental study on ultrasonic vibration honing
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1420
The current research of the ultrasonic vibration assisted machining technology focused on the experimental analysis. And there are only simple theoretical introductions, which have not formed the systematic theory. Power ultrasonic vibration honing technology is more systematically studied from the kinematics point of view in this paper. And the four kinetic characteristics of the ultrasonic vibration honing have been summed up: power ultrasonic honing process is essentially the new process which is continuous at macro level and separate at micro level; which is an energy concentration, high-frequency impact of intermittent cutting process; and it is the process of the united pressure of the reciprocating cutting and ironing. In addition the roughness comparison test between ultrasonic vibration honing and general honing is also carried and the results show that the ultrasonic vibration honing have the significant effect of reduction in surface roughness. (4 pages)Experiments study of ultrasonical combined electrical micromachining micro-structures on working surface of friction units
http://dl-live.theiet.org/content/conferences/10.1049/cp.2009.1408
For manufacturing micro-structures on working surface of friction units, the ultrosonical combined electrical micromachining is advanced as a new technology. The ultrosonical combined electrical micro-machining system is built and improved L which machining parameters can be adjusted in a wide ranges. The micro USM & EDM (ultrosonical combined electro-discharge micro-machining) and micro USM & ECM (ultrosonical combined electrochemical micro-machining) can be achieved with the micro-machining system. The round section micro electrodes in different sizes are manufactured by combined electro-discharge micro-machining. The micro-machining tests are carried. The process properties of the combined electrical machining are analyzed and studied. The possibility and the technology advantages have been proved, that is the good machining precision, lower cost and high efficiency. The friction characteristics of surface with round micro-structures are analyzed. The friction tests are carried. It is verified that friction surfaces with regular profiles round micro-pits have lest friction coefficient and wear. It is very helpful for improving the friction performances and prolonging working life of important friction units. (5 pages)Motion compensated complementary coding for medical ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080646
Ultrasonic imaging using complementary coded pulses offers the SNR improvements of signal coding without the filter side-lobes introduced by single transmit codes. The effects of the transducer and motion in the medium, however, can introduce mismatch artefacts and high side-lobes due to misalignment. A method for filtering and motion compensation of complementary coded signals appropriate for use in medical imaging scenarios is presented in this paper. The method has been shown by simulation to reduce side-lobes to levels that compare favourably to systems using FM-coded signals of similar length and bandwidth while increasing coding gain and range resolution.Restoration of medical ultrasound images via modified homomorphic deconvolution
http://dl-live.theiet.org/content/conferences/10.1049/cp_20080366
Compared with other medical imaging devices, ultrasound imaging suffers from its poor resolution. Therefore, in order to obtain the important diagnostic image detail, restoration procedure need to be performed. The paper describes a modified homomorphic deconvolution which is used to improve the quality of medical ultrasound image. The proposed deconvolution performs the homomorphic filtering based on the estimation of the point-spread function (PSF). Especially, the application of a non-local means (NL-means) algorithm makes PSF estimation more precise for rejecting the white-Gaussian noise (WGN) effectively. We validate our method for different radio-frequency (RF) images with resolution improvement.Ultrasonic distance measurement method based on software radio spread spectrum
http://dl-live.theiet.org/content/conferences/10.1049/cp_20070769
Based on the research on software radio and spread spectrum technology used in radar system, one method of spread spectrum method ultrasonic distance measurement based on software radio is proposed. An appropriate pseudo random number (PRN) is modulated and transmitted by ultrasonic sensor. The time of flight is calculated by using software radio technology. Receiving signals are normalized by band pass sampling filter and 1 bit normalization method. The phase difference between the sending signal and receiving signal is captured by digital matched filter (DMF). This method shortens the processing time and reduces FPGA resource. The system design is based on Aletra's quartus II software, and it fits to FPGA chip after logic synthesizing and placement routing. The timing simulation result in placement and routing is presented. According to PRN code capture principle in spread spectrum correspondence, digital matched filter based on 1 bit quantification technology is carried out. Comparing with traditional digital matched filter, this method reduces the FPGA resources consumption to 1/24 at least. The simulation testing results indicate that spread spectrum method ultrasonic distance measurement based on software radio is feasible.Spontaneous Brillouin scattering modelling and measurement in various axisymmetric optical fibres
http://dl-live.theiet.org/content/conferences/10.1049/ic_20070400
We describe a computation method of spontaneous Brillouin scattering process using a simple original acoustic mode analysis. Numerical results have been compared with measured Brillouin spectra for two different commercially available fibres. (2 pages)Patient compatibility of devices
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060300
This paper discusses the patient compatibility of medical devices. A device is said to be patient compatible if it meets the regulatory requirements of safety, functionality and is according to the Annex 1 of the European Medical Device Directive. As it is accepted that medical devices constitute a risk, the benefits of the device should outweight the risks. The risk should be minimised hence a risk management programme must be undertaken. The relevance of device encapsulation is also discussed. If some materials are not biocompatible, they must be covered or encapsulated. A case study on an intravascular ultrasound (IVUS) coronary catheter is presented.Resonant acoustic profiling
http://dl-live.theiet.org/content/conferences/10.1049/ic_20060429
The article consists of a Powerpoint presentation on resonant acoustic profiling technology. The areas discussed include: components of RAP technology; antibody specificity; mouse IgG concentration analysis; IL-1β detection and interaction; serum detection; cell expression media; multi-protein complex formation; drug-enzyme profiling; kinetics of drug binding; bacteria detection; inflammatory marker; etc.Effects of ultrasonic impact treatment on the residual stress and fatigue performance of ultrahigh strength steel weld joint
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060746
Using special ultrasonic impact treatment (UIT) equipment treated butt welded joint of ultrahigh strength steel (σ<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">b</sub>=1600MPa). The surface residual stress test of the butt welded joint of ultrahigh strength steel both in the as-welded conditions and ultrasonic impact treated conditions were performed by X-ray diffraction instrument. And the fatigue performance tests of the butt welded joint both in the as-welded conditions and UIT conditions were performed, too. The test results are as follows: (1) In as-welded condition, there is 180Mpa residual tension stress near the weld toe. While in ultrasonic impact treated condition, there is -350Mpa residual compression stress near the weld toe. The residual stress of the welded joint specimen treated by UIT reduced 300%. (2) The geometry of weld toe is rounded off by UIT, and the stress concentration level was reduced near the weld toe. (3) In as-welded condition, the fatigue strength Δσ(2×10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">6</sup>) of welded specimen is about 141MPa, and that of specimen in UIT condition is about 188MPa. The fatigue strength of welded specimen treated by UIT increases by 33.3%. Fatigue performance of ultrahigh strength steel welded joint was improved by ultrasonic impact treatment.An application of the neural network in the near-field acoustic holography
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060952
The near-field acoustic holography (NAH) is an effective and useful noise measurement method. There are many methods for reconstruction of the sound source, but the measurement circumstance is limited and the random noise is unavoidable. In this paper, a new holography reconstruction method based on neural network (NN) is proposed, which can identify the sound source and restrain the random noise better neural network (NN) is widely used in many fields recently. It has many main characters, such as the ability of learning and nonlinear approximation capability. In order to improve the measurement accuracy, a suitable net structure and learning algorithm of NN need to be found. The sound pressure distribution is measured as input and K-L transformation is applied to extract the input. Output is the distribution of the noise sound. Experiment results indicate that the method can identify the noise source effectively. Under the condition with random noise, it is also effective and accurate. In conclusion, the reconstruction method based on NN is more accurate and more applicable.Improved assessment of pulsatile blood flow during resuscitation using Doppler ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060357
Early defibrillation is critical for successful resuscitation of a sudden cardiac arrest patient. Defibrillators currently do not assess the patient's heartbeat or blood circulation and the responder has to manually check for the pulse, a procedure known to be very inaccurate. Previously we had developed an ultrasound Doppler based approach to determine the presence of blood flow in the context of resuscitation. Here we extend our earlier work to develop a generalized pulsation index based on a spectral analysis of the Doppler signal. This new method has the advantage to better distinguish between states of pulse and pulselessness, since it aims at capturing the essentially non-sinusoidal behaviour of cardiac activity. In turn, this leads to better sensitivity and specificity for pulsatile flow assessment. The method was demonstrated on data from pigs undergoing cardiac arrest and defibrillation. (4 pages)The design and finite element analysis for the ultrasonic amplitude transformer bar
http://dl-live.theiet.org/content/conferences/10.1049/cp_20061056
Ultrasonic amplitude transformer bar is an important part in the power ultrasonic vibration systems. With an application example, a half-wavelength amplitude transformer bar of conical type is designed by analytical method. The freedom modal analysis on the transformer bar was made with finite element analysis software ANSYS, and the natural frequency of transformer bar was obtained. Finally the transformer bar with attached tool was amended by method of finite element analysis, and the purpose of amendment can make the certain natural frequency equal to the operating frequency of vibration system, so as to make sure that transformer bar can lengthways resonate reliably when it is stimulated.Application of pulsed power generated high power ultrasound to waste comminution and the recovery of metals
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050050
The disposal of waste materials is an increasing burden on industry across the world. In order to address this problem, the development of viable technologies and recycling paths is required. Often it is necessary to process waste to reduce its size (comminution) or to allow the recovery of high value components entrapped in waste. This paper describes the application of high power ultrasound (HPU), generated using pulsed power techniques, to two waste products: glass and stainless steel slag. (6 pages)A bootstrap approach to testing for an association between bursts in the neonatal EEG and changes in cerebral blood flow
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050324
In normal premature neonates, a pattern of EEG, known as trace discontinu, is common, which contains bursts of relatively high voltage, in an otherwise lower voltage background. The current work investigates whether these bursts are associated with changes in the velocity of blood, measured by transcranial Doppler ultrasound in the middle cerebral artery. A measure of consistency in the response from repeated bursts is proposed, and in order to test its significance, a bootstrap method was devised. With this method signals that are interrupted by `missing samples', where segments of the signal are lost due to excessive noise or artifact (as was the case in our recordings), can also be analysed. Monte Carlo simulation studies demonstrate the potential of this approach. In tests on 12 recordings from premature babies it was found that 3 had significantly consistent responses, with a peak in cerebral blood flow velocity some 5-12 seconds after the onset of the bursts. Overall, the results suggest that there is an association between bursts and blood-flow, at least in some subjects, but the causal mechanisms require further studies.Improved detection of embolic signals using multi scale wavelet filtering, AR and ANN, for TCD ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/ic_20050332
Transcranial Doppler ultrasound can be used to detect emboli in blood flow in the brain. The presence of emboli is an indication of high risk of stroke. Embolic signals have characteristic transient chirps suitable for wavelet analysis. We have implemented an on-line intelligent wavelet pre-filter combined with a new frequency based neural network classification system (NFS) to produce a new online detection system. Initial results show an improvement in accuracy compared with the widely used FS-1 system. Our system makes, use of multi-scale wavelet denoising using an adaptive coefficient threshold. The pre-filtering system is combined with a detection system which uses a two layer neural classifier and a new auto-regressive event detector. For conditions such as carotid stenosis an improvement of 20% in detection accuracy was obtained. Our online (real time) intelligent wavelet amplifier and its matrix optimised form uses the matched filter properties of multiple coefficients from multiple wavelets to significantly enhance embolic signals and improve classification performance.A reduced forward operator for acoustic scattering problems
http://dl-live.theiet.org/content/conferences/10.1049/cp_20050327
This paper describes the development of a reduced forward operator for solving acoustic scattering problems that arise in ultrasonic imaging applications. The reduction, inspired by the contrast source inversion technique, is obtained by decoupling the interaction between locations in the computational domain at which contrast is present and those positions at which there is a zero contrast. The decoupling is achieved by multiplication by a diagonal matrix whose entries reflect the presence or absence of contrast at the associated point. Numerical results confirm that the reduced operator produces convergent results in less iterations.An ultrasonic-based enuresis treatment device
http://dl-live.theiet.org/content/conferences/10.1049/cp_20040588
Primary nocturnal enuresis is characterised by an involuntary discharge of urine which happens unconsciously during the night. Enuresis can be treated by means of a conditioning device that wakens the wearer once the bladder volume has reached a preestablished threshold of capacity. Existing research using this preemptive technique indicates good results. However, deep sleep and inability to waken limits its effectiveness. The paper describes an intelligent ultrasonic-based bladder volume monitor and alarm system which enables investigation of multiple complex wakening sounds and stimuli. The proposed system also accurately logs all events for support of on-going research.Workforces in complex environments - a railway maintenance case study
http://dl-live.theiet.org/content/conferences/10.1049/ic_20030279
Assuring the appropriate quality and safe performance of the wheel-rail interface requires skilled interventions of many different types. The authors of the present paper have studied one particular set of activities that forms part of the overall track maintenance task, namely, the assessment of rails for fitness for purpose using visual inspection and ultrasonic testing. The paper is based on interviews with track workers and observations collected as part of a sociological study of railway track maintenance systems conceived in the aftermath of the Hatfield accident of October 2000. Quotations and excerpts from interviews are marked thus [Int. xy], while conversations during fieldwork are marked [FW. xy]. (13 pages)PhiSAS: a low-cost medical system for the observation of respiratory dysfunction
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020042
Respiratory illness is recognised internationally as one of the commonest medical disorders affecting the world's populous, and is especially a major problem that affects the third world. The World Health Organisation (WHO) pursues an extensive health program that is aimed at reducing the plight of respiratory disorders by treatment and education. As with the majority of third-world health care programs, the effectiveness is limited by the availability of resources and finance. PhiSAS (Physiological Signal Analysis System) is a novel system developed for the observation of lung sounds. The system consists of a Personal Computer (PC) supported with dedicated software and hardware. Lung sounds can be recorded via chest microphones into the computer system for storage in digital form. This data can then be retrieved for post-processing using an array of software-based Digital Signal Processing (DSP) techniques that can mathematically manipulate lung sounds to extract important features. Data and results can be presented audibly by sound playback, or graphically by using spectrographs. The spectrograph is a representation of lung sound spectral energy with respect to time and frequency. PhiSAS has the ability to present three types of analysis based on conventional and novel mathematical techniques: Fourier, Wavelet and Time-Frequency Analysis. The purpose of the PhiSAS system is to provide objective analysis of lung sounds. The practice of auscultation (the art of listening to body sounds) has been practiced by physicians since the days of Hippocratic medicine. However, many physicians believe that respiratory auscultation performed with a stethoscope offers little scientific value due to the way it is practiced. For example, observations can be subjective depending on the physicians hearing ability and experience. Moreover, descriptions of lung sounds are described using onomatopoeic references that are ambiguous. By exploiting advances in low-cost PC technology and techniques in signal analysis, the physician can express sound observations in a more precise scientific manner. (5 pages)Heart sound segmentation by hidden Markov models
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020297
The segmentation of phonocardiogram (PCG) signals is the first step in the automatic diagnosis based on heart sounds. The majority of attempts to segment PCG signals depend on a reference provided by simultaneous electrocardiogram recordings. The algorithm proposed in this paper is based on the analysis of the PCG signal only and does not require an ECG reference signal. In this paper we propose the tracking of the log spectral components that vary slowly with frequency (the low-time components). That is Cepstral analysis is used to provide the features selected to represent the heart sounds. The algorithm utilises a hidden Markov Model to identify the S1 and S2 components of the heart sound, which delimit the systolic and diastolic cycles. The parameters of a simple hidden Markov model with single Gaussian distribution for continuous observations are learned from a training set of heart sounds. Once the parameters of the model are obtained PCG signals from different sets are used to test the segmentation procedure. (4 pages)Speckle reduction techniques in B-mode ultrasound images
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020288
The traditional 1D spilt spectrum processing (SSP) method suffers from a relatively high-resolution loss limitation, inherent to the method. There is a trade-off between speckle reduction and resolution loss. On the other hand, the new 2D SSP with directive filters perform well. In this method, the filters are chosen to have a bandwidth larger than that of the ultrasound pulse and this helps to maintain image resolution. Even though SSP is a single-image method, it tackles the speckle reduction problem in a similar way to frequency compounding (a multi-image method), where a set of images from the same structure is acquired by using ultrasound pulses with different frequencies for each image. Likewise, the use of directive filters in the (single image) 2D SSP method has a similarity with angle compounding method (a multi-image method), where a number of images are acquired from different scanning angles in order to decorrelate the speckle. However, practical difficulties with the use of angle compounding methods in a medical context are overcome by the new 2D SSP with directive filters, which requires only a single image. The zero adjustment processing (ZAP) is a very powerful method, and is the only technique that can recover the apparent energy loss suffered in destructive interference, and promises well for further development. The hybrid method was used to demonstrate the synergy between different techniques, and the concept certainly looks ripe for further development. (6 pages)A novel approach for non-stationary medical signal analysis using Hilbert spectrum
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020292
This paper discusses a novel method to study the nonlinear and non-stationary processes and to investigate the time-varying frequency of the practical medical signals. The aim of this contribution is to explore the role that both empirical mode decomposition and Hilbert transform can be used to play in such medical signals. A Hilbert transform is applied to each intrinsic mode function to obtain the global time-frequency distribution of the underlying signal with a point of view of instantaneous frequency. Two kinds of clinical phonocardiogram signals with normal and abnormal cardiac functions were analyzed by using the proposed method. The instantaneous frequency distributions of the PCG signals were also compared with the results by using the wavelet transform. Both simulation and experimental results were presented and discussed to demonstrate the power and effectiveness of the proposed new approach. (6 pages)Comparison of transformation methods to determine frequency specific cochlear hearing loss based on TEOAE
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020294
In this paper, we aim to determine frequency-specific cochlear hearing loss (HL) by means of transient evoked otoacoustic emissions (TEOAE). Exemplarily, the differentiation of three groups of frequency-specific HL is performed by parametrisation of the time-domain TEOAE responses based on three transforms, namely discrete wavelet transformation, wavelet packets and Gabor frames. Using an SNR-like criterion, the various transforms are tested for their ability to differentiate between the three groups of hearing ability. This differentiation is evaluated on a large group of data from patients. The separability results for each transform method are checked against the data of a second control group. (6 pages)Fuzzy, Weighted-Offset, Multiscale Edge Detection for automatic echocardiographic LV boundary extraction
http://dl-live.theiet.org/content/conferences/10.1049/ic_20020289
This paper describes a new Fuzzy, Weighted-Offset, Multiscale Edge Detection algorithm for cardiac left ventricular (LV) epicardial and endocardial boundary detection on short axis (SA) echocardiographic images. The proposed method uses the `centre-based' approach, previously described in S.K. Setarehdan and J.J. Soraghan, 1999, IEEE Transaction on Biomedical Engineering. Vol. 46, No. 11, 1364 - 1378. The Edge-detection stage uses a new Fuzzy Weighted Offset Multiscale Edge Detection (FWOMED) technique in order to identify a single moving point for each one of the epicardial and endocardial boundaries over the N radii in an echocardiographic frame. This technique achieves optimal edge detection through non-decimated wavelet decomposition of the original signal followed by a fuzzy based decision technique, which is applied across the scales. Finally, a uniform cubic B-spline approximation is used to define the closed LV boundaries. The performance of this technique is compared to Mallat's (S. Mallat and S. Zhong, 1992, IEEE Trans. PAMI, Vol. 14, No. 7, 710-723.) multiscale edge detection technique, for a range of test data sets comprising different synthetic noisy signals. (6 pages)Introducing transmission line matrix (TLM) modeling and its application in medical ultrasound
http://dl-live.theiet.org/content/conferences/10.1049/cp_20000340
Transmission line matrix (TLM) modeling is a numerical technique for modeling wave propagation. It was used originally for modeling electromagnetic waves. P.P.M. So et al. (1991) introduced the inverse TLM, which is TLM in time reversal. In this paper, we introduce TLM modeling and inverse TLM modeling and explain how it would be used for modeling ultrasound waves. Some applications of TLM modeling in medical ultrasound systems are also proposed.Determination of the shock wave intensity from a laser lithotriptor using a bi-laminar hydrophone
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990493
Kidney stones have been treated for some years with extracorporeal shock wave lithotripsy (ESWL) with marked success but this therapy is contraindicated under certain circumstances. In addition, some types of kidney stone do not respond to ESWL and the reason for this is not fully understood although the materials from which the stone are formed is thought to be a crucial factor. An alternative technique uses a laser, which discharges into the urine surrounding the stone and thereby initiates a shock wave. The interaction of this shock wave with the stone is only poorly understood. In order to examine this situation further, artificial stones were created whose material and elastic properties were calculated by ultrasonic methods. The shock wave induced pressures within the stone could then be calculated once the shock wave intensity had been measured. Measuring the shock wave intensity was performed by the use of a bi-laminar hydrophone. The variation in the shock intensity as a function of the laser discharge-hydrophone separation was measured which permitted the intensity at the point of discharge to be estimated. Pressures up to 500 MPa have been measured which is well in excess of the fracture strength of the stones. (5 pages)Acoustic emission in aerospace structures
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990189
We have shown how four sensors can be used to investigate the location of acoustic emission in aerospace structures and how the effective propagation speed can be calculated on an event by event basis. We have also investigated the possible multiplicity of solutions and used a sensitivity analysis to obtain a maximum entropy deconvolution of an acoustic emission map. We have finally shown how embedding methods can be used to divide the signal into separate components which can be treated as “virtual” sensors. (5 pages)Forward modelling of ultrasound fields using a novel directivity spectrum method
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990109
A new technique for computing images of transient ultrasound fields is presented. The theory of the method is based on the “directivity spectrum”, which is a generalisation of the angular spectrum. The method, in contrast to the angular spectrum approach, is particularly suited to the computation of transient fields, and it contains no evanescent waves. It allows computed pulse propagation over extended ranges. (3 pages)Modelling the ultrasonic inspection of smooth and rough planar defects
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990106
A suite of computer codes has been developed for the theoretical modelling of ultrasonic inspection in ferritic steel. The models predict the echo amplitudes from postulated planar defects in direct pulse-echo, “corner effect”, tandem or TOFD configurations. In general the defects are assumed to be smooth, but for direct pulse-echo a model is also available for rough defects. The models are mostly used to establish the capability of a proposed inspection procedure to detect hypothetical defects which could be of structural concern. They have an important role in providing evidence for technical justifications when qualifying inspections using the methodology described by ENIQ (the European Network for Inspection Qualification). This paper will describe the range of models currently available in the authors' companies, concentrating on recent developments. In particular the important issue of the validation of models against experiment will be discussed. Finally, some typical examples of use of the models will be briefly described. (4 pages)Modelling of pulse-echo scattering using a water-coupled transducer
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990112
This paper outlines some new developments in the modelling of a commonly found industrial situation where a water-coupled transducer is used to interrogate defects in a solid. The echo signals recorded back at the transducer need to be interpreted (or inverted) in order to characterise those defects. In particular we will look at the new finite-difference modelling of this problem, and show that it allows very accurate predictions to be made of signals from known defects. We will also consider other approaches that give insight into the physical processes involved in the wave scattering and echo formation. In time these methods-taken together-could lead to an accurate inversion procedure for this problem for a wide range of defects. (4 pages)Multiple-technique NDT simulations of realistic configurations at the French Atomic Energy Commission (CEA)
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990107
The ability of models to deal with accurate descriptions of the piece geometry and materials (by CAD) is a key-point for simulation work. Availability of semi-analytical models for simulating sensor and actuator behaviours and the interaction of the “field” with the piece allows both versatility and efficiency. Simulation tools developed at CEA for NDT of realistic configurations have been presented. Ultrasonic, radiographic and eddy-current techniques are considered. They are based on semi-analytical formulations for efficiency. Numerical integration is performed wherever necessary for generality. They are included in a general software CIVA allowing the processing, the imaging and the simulation of NDT data. Simulations are used as laboratory tools for conceiving and qualifying methods and demonstrating their performance, teaching and training operators. They are also used in field work context for in-service inspections to help experts' interpretation, by direct simulation of their guess for immediate comparison with actual data or by means of model-based inversion algorithms. (4 pages)A model for predicting ultrasonic fields in complex structures and configurations
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990108
Quantitative prediction of the field radiated by a transducer into a given piece is a fundamental tool for inspection qualification and for understanding actual results. Pieces of complex structure are often involved (e.g. welds, cladded components) leading to complex wavepaths including reflection and mode-conversion. The model Champ-Sons is developed at the French Atomic Energy Commission for ultrasonic field prediction. It is semi-analytical for computer efficiency. The theory is first described. The modelling of transducer behaviour is presented for typical transducers used in NDT. Definition of the piece by CAD software is discussed. (4 pages)Online monitoring and characterisation of mineral deposits in petroleum pipelines
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990725
Progressive deposition of scales in petroleum pipelines leads to large production losses. Remedial chemical de-scaling operations require the knowledge of the composition and thickness of these deposits to minimise expensive chemical wastage and costly production shutdowns. Although some work has been reported to measure wax and hydrates in gas pipes, there are no on-line techniques to address the problem of scale assessment. In this regard, some feasibility studies have been previously carried out to develop novel techniques, under ideal laboratory conditions. This paper presents an overview of the work carried out in developing novel ultrasonic monitoring techniques and advances towards the development of scale early warning techniques to detect scale nucleation and monitor early stage growth. The work carried out on sonic enhancement of dissolution during chemical de-scaling is also presented. The overall project branches out into three main areas, namely: (1) top-side monitoring of scale deposits, (2) down-hole monitoring and characterisation, and (3) sonic enhancement of scale dissolution. (7 pages)Developments in NDT techniques for use in the offshore industry
http://dl-live.theiet.org/content/conferences/10.1049/ic_19990723
Several novel, rapid inspection techniques have become available for the noninvasive inspection of plant components, thus helping effective inspection to be performed with minimum interruption to production, These techniques are being used to help the plant owners operate more cost effectively in the current offshore economic climate. This paper describes some of the techniques including: INCOTEST, a pulsed eddy current system; real time radiography; LORUS, long range ultrasonics; magnetic flux leakage tools; and MAPSCAN, ultrasonic C-scan mapping. (5 pages)Regulation for new technology in gas metering
http://dl-live.theiet.org/content/conferences/10.1049/cp_19990095
There is a need for flexibility in the regulatory approach to measuring instruments to allow for changes in technology, in order to cater for technological advance. The introduction of the E6 ultrasonic domestic gas meter in the UK illustrates the principles involved. It is important to control gas meter accuracy. Recognising this, the government made Ofgas the legal authority or Notified Body responsible for regulating meter accuracy. Changes were made to national legislation to allow for the use of ultrasonic metering technology. In the near future further changes will be made to national legislation to allow for the use of temperature converted meters. This is only the start of an approach which, with adoption of the Measuring Instrument Directive, will result in regulations which are independent of technology. This freedom will encourage innovation in those responsible for metering solutions in future years, while maintaining fair trade and consumer protection.One sensor learning from another
http://dl-live.theiet.org/content/conferences/10.1049/cp_19991202
Sensor interpretation in mobile robots often involves an inverse sensor model of the sensors used. Building inverse sensor models for sonar sensor assemblies is a particularly difficult problem that has received much attention in past years. A common solution is to train neural networks using supervised learning. However, large amounts of training data are typically needed, consisting, for example, of scans of recorded sonar data which are labeled with manually constructed teacher maps. Obtaining these training data is an error-prone and time-consuming process. We suggest that it can be avoided, if an additional sensor like a laser scanner is also available which can act as the feeding signal. We show successfully trained inverse sensor models for sonar interpretation using laser scan data.Obstruction detector using ultrasonic sensors for upgrading the safety of a level crossing
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980140
The authors have developed a new obstruction detector, that can be useful for all railway lines including ones in snow-covered areas, by studying ultrasonic-based obstruction detection at a crossing. In this paper, the authors explain the structure and the methods of the ultrasonic-based obstruction detector first, then about the safety logic of the detection.Prodding to detect mines: a technique with a future
http://dl-live.theiet.org/content/conferences/10.1049/cp_19980713
The advantage of `close-in' detection, requiring transducers to be actually introduced into the soil covering a landmine, has been argued. Experiments with mechanically assisted rotating prodders shows that they can penetrate even very hard dry soils at low force and high speed, provided the soils are homogeneous. The speed of penetration is roughly proportional to the speed of rotation of the prodder up to very high values around 20000 rpm. Less homogeneous soils, e.g. those containing gravel, can also be penetrated at speed provided a more brush-like tool is used. Simple smart prodders, with low power consumption and a well-designed user interface, can offer a significant improvement in the quantity of information available to a deminer who is attempting to discriminate between a mine and other objects.Reconfigurable FPGAs for data compression in ultrasonic non-destructive testing
http://dl-live.theiet.org/content/conferences/10.1049/ic_19971003
Ultrasonic imaging techniques are long established in the medical field, but have not found the same level of acceptance in nondestructive testing (NDT). Operators of NDT equipment are less comfortable using 2D images despite the easier flaw characterisation which they permit. However, where the specific requirement is rapid inspection of large areas, the generation of a cross-sectional image in real time can deliver a benefit by reducing inspection time. The DSL Flaw Imager, which was developed using medical application techniques, has found a use in this field, but to address a potentially larger market the size, weight and cost of the instrument must be reduced. This can be achieved by the use of reconfigurable computing elements to implement the essential data compression. Reconfigurable computing features field programmable gate arrays (FPGAs) performing a variety of operations in hardware, the control program being executed on a microprocessor. This reconfigurability provides an advantage, in that sections can be powered down when not in use, or a new configuration program introduced to implement analysis algorithms. More vital to this work is the fast microprocessor interface of one implementation of this emerging technology, the Xilinx XC6200 reconfigurable development system, which allows the reconfigurable unit to interface with a controlling PC while still operating at the high processing speeds required. An end user's perspective is offered on practical experience with this system for the described application. (4 pages)Non-linear acoustics and adhesion measurements of interfaces: techniques for the inspection of bonded structures
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970051
At the present state-of-the-art, nondestructive testing techniques can only distinguish between a complete delamination or complete bonding. It is difficult to judge an intermediate state of bonding. With the technique presented, this gap can be closed. However, much more theoretical work has to be undertaken in order to obtain an absolute calibration of the technique and to strengthen its application. From a practical point of view, probes have to be developed which are linear at least up to the strains and existing electronic equipment has to be adapted. (4 pages)Modelling and instrumentation applied to the NDE of adhered metal joints
http://dl-live.theiet.org/content/conferences/10.1049/ic_19970049
Reviews recent progress in modelling of compression wave systems in adhered joints, the development of advanced instrumentation which was the outcome of the modelling programme, and novel Lamb wave cum neural network techniques for bondline dimension estimation. (3 pages)