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Is it possible to use EDDY CURRENT TESTING Nondestructive testing method to check Inter-metalic phase of Duplex Steel pipes?
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Thank you Depivers
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The ultrasonic machine preferred is5Mhz capacity . The specimen used is Fiber metal laminate. Transducers using are Apprx.1 inch, so maintaining a focal length of 25.4mm between the specimen and the transducer. while performing through transmission pulse mode ,I have observed the echo transmission in the ominiscan are yellow in color, After placing the specimen the yellow color echo transmission are converted to green color. i have varied the Gain in the UT setting and threshold was set to 90%. even though green echo transmission are appeared on the screen . Also i am not able to capture the damage area of the specimen . The obtained image is attached .will any body help in resolving the problem i am facing to get the out put.
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The green echoes are just a display mode called envelope. This mode holds the signal on the screen. To turn it off i believe it is in Display > Overlay > A-scan > Envelope.
I am not 100% sure on your setup or what your damage mechanism is, but the through transmission method (2 probes, one on either side of the specimen) will only indicate discontinuities through a lack of response.
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I did an experiment on a glass composite thin plate and generated Lamb wave. I increased the stiffness of the plate by forming a sandwich structure. I could find Ao mode with very attenuated amplitude but So is very diminishing. Confused, as per my understanding, I should get both modes frequencies even if the amplitude is small. But only Ao I could obtain its frequency but So not.
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The dimensions of the thin plate, the configuration of shaker or input device, support and/or constraint of the specimen during testing, the location or distribution of area being measured for signal to test for Ao & So, as well as what transducer(s) or optical technique(s) is/are being used for those measurements, and what circuits and software are being used to condition and process the signal after acquisition.
The are many reasons that may be causing attenuation or lack of effective detection or isolation of the desired or expected signals, including that they actually may not be there at sufficient energy level for effective detection. Are you sure your estimated values for So of the increased-thickness sandwich plate are reasonable and don't actually predict the lower So values? Are you measuring 'lamb' waves on one skin of the sandwich only or of the entire plate (i.e. do you have transducers on both surfaces of the plate with careful and accurate reproduction of phase in both cases, and relative to one and other? Do you isolate or effectively filter frequency or wavelength anywhere in the process of your data collection, conditioning and/or post-acquisition processing? Are the 'lamb' waves on the skin or in the overall plate, what is the ratio of characteristic wavelength to plate thickness and how did this change by your structural alteration?).
Without knowing more of your setup, you experiment and your instrumentation, it is difficult or impossible to offer meaningful guidance.
In terms of a general vibration measurement problem, what signal are you expecting and why? Does the measured value represent something that seems impossible or not, it the result within or nearly within the expected range, and if not, is there something in the method or instrumentation or conditioning/processing that might explain any observed discrepancy? Hope this helps.... -TH
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What methods can be named to measure the temperature of a surface considering below assumptions and limitations, except for Thermography?
- Measurement of only one or a few spots is enough, and there is no necessity to measure the entire surface and display a thermal map as same as the Thermography technique.
- The methods should not be related to infrared techniques and radiation emitted from the surface.
- Without any contact and with a normal distance for inspection (NDT or SHM) like 0.5 m.
If there is no method with considering the final limitation (non-contact), this restriction can be ignored.
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Temperature measurement, surface temperature, intelligent pyrometer
The non-contact thermometer ensures precise ... Show details · Navigation: Applications · Industries Search by measurement · Acceleration & ...
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Using Abaqus, I am trying to generate symmetric lamb wave mode in a simple Aluminum plate by applying symmetric point force parallel to the plate. The extra wave followed by the S0 mode appears all the time. This is definitely not the A0 mode because the geometry is symmetric and hence no mode conversion would take place, these are not the reflections from the boundary, I am new in this topic and I need some guidance,
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You have a wave packet due to the the impact on the plate. We do not know where is the environment of the plate. The trailing packets can be excited by a far reflection from the boundary the enclosure of the plate.
I proposed this hypnosis because as you see the second wave packet is attenuated relative to the first wave packet. So, i assume trailing pulses are echos of the first pulse. They may come from a far boundary to the plate.
Best wishes
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I am doing a reserch on infrared thermography inside industrial furnaces, and I am not sure about why a camera sensitive to 3.9μm wavelength radiation cannot see flames due to natural gas combustion.
Does it have something to do with the emission spectrum of the flue gas?
Do you know any article or book talking about this topic?
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The infrared spectra for a natural gas flame has a peak at 4.2 to 4.7 μm due to emissions from CO2. There is also a peak between 2.4 to 3 μm due to emissions from H2O and CO2. Then there is a broad band peak between 0.4 and 3.5 μm (dependent on the flame temperature). Cameras in the range 0.8 to 1.1 μm are typically used for higher temperatures typically above 600oC. Therefore any infrared camera that operates in ranges below 5 μm should work, provided it is not restricted to the 3.9 μm band, should see flames.
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I am trying to find the pixel vales by using DAS algorithm, I have calculated the envelope of the signals by using Hilbert transform and then calculated the arrival time of a signal traveling from the actuator to the arbitrary pixel value (x,y) and then to the sensor, they actually form multiple ellipse but I cant figure out the next step to obtain the image value, E(x, y). The general formula of DAS is attached. Someone please help me.
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I don't know your problem exactly, but i can guide you how to implement this in Matlab or some other software. Follow the steps in software coding:
1. First what is i,j. Fix it. What is u and v?
2. Find t(x,y) value using the given formula.
3. Second step evaluate u and v.
4. Third step find rij.
5. Its not simple. You should interrupt like this
rij(t(x,y)) =
6. Then find E(x,y)
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I am running a round robin test (from August to December 2018) of 3 selected parts in Ti6Al4V and fixed microCT test guidelines and processing workflow - the aim is to check that all participants get the same information from microCT scans of these known test parts. If any discrepancies we will explain the reason behind it. It is a relatively simple procedure clearly outlined and each participant has max 2 weeks. We would like to have a wide spread across industry and academia, please contact me if you have an interest and would like to take part.
You need
1. A microCT scanner that can go up to 200kV
2. Good image analysis software, preferably VGSTUDIO MAX, but others OK if you figure out the required modifications to the workflow yourself
3. Able to do scans and processing within a 2 week period, free of charge, and send the parts on the to next participant
Please send me a message for more detailed information
Thanks
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Thanks to everyone who contributed and showed interest in this work. The final article is found here, with 50 days free access from today 21/09/2019: https://authors.elsevier.com/a/1ZmZs7tcTWXHTP. Enjoy the paper and thanks for your interest. #additivemanufacturing #microCT
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какие методы неразрушающего контроля можно отследить образование зародышей трещин?
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Рами Карми прав! Акустическая эмиссия лучший известный метод. Но можно и методом с использованием эффекта Горбунова . Без дополнительных механических усилий.
Сканирующая контактная потенциометрия требует приложения (накладывания) специальных поверхностных контактов. Метод с эффектом Горбунова не требует этих операций. Обладает чувствительностью на порядок выше чем сканирующая контактная потенциопетрия.
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Excuse me professor:
I am from Chongqing University of Technology. I am currently using an ultrasonic pulse generator, a pair of underwater ultrasound transducer(80KHz), oscilloscope to test the hardness of kiwi fruit, despite the hardness of the kiwi fruit is obvious gap, but I don’t find the difference in the ultrasonic wave, could you tell me the reason? 
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Dear Zhang
I hope that these articles will be useful to you.
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I would like to know if anyone is pursuing research on mechanical characterization/testing at high temperatures (above 1000C) but using non-contact deformation measurement techniques?
Do you still use strain gauges or extensometers? What are the challenges faced using conventional displacement or strain measurement techniques for quasi-static loading at high temperatures? 
We have developed a unique non-contact deformation profile measurement system capable of testing samples up to 1600C using wide variety of sensors - ranging from laser triangulation based techniques to confocal and interferometry based sensors. More details can be found on my profile page.
We are looking forward to collaborating with interested researchers to develop the system beyond current functional capabilities. Message me through researchgate for your queries and interest.
With Best Regards,
Prasad
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Thank you Mr. Leicht. I will try to contact Dr. Holger Friedrich from the link you provided.
Best Regards,
Prasad
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It is well-known that the speed of acoustic waves in solids can bring useful information on the involved elastic moduli, whether longitudinal or transverse waves are used, therefore giving access to Poisson ratio for example. But is the same possible with highly porous materials, which intrinsically absorb acoustic waves ? Decreasing the wave frequency helps but then the wavelength becomes quickly too high with respect to the sample size. Is there any technical solution ? Any other non-destructive method you may suggest for characterising the mechanical properties of highly porous solids ?
Thanks
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Dear All,
I finally found the solution: the quasi-static mechanical analyser QMA-X from Mecanum. It uses a non-destructive method for determining elastic modulus and Poisson ratio of very weak, highly porous, materials. The very low frequency that it is used allows doing this kind of measurement for highly attenuating materials. Moreover, it complies with the ISO 18437-5 standard.
Have a look at the flyer, here attached.
Alain
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Is there any nondestructive test to check the case depht in induction hardened steels?
If not, can I rely on the results of an speciment produced attached to working part?
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Hi, try to use the ultrasonic waves inspection. Use the reflecting pulse method to calculate the depth of the defect from the specimen surface. The transmission pulse method can detect the presence of the defect only. Good luck.
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I have used a Q-switched Nd:YAG laser for generating the ultrasound and the receiver is a piezoelectric transducer.
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Aside from Oleg's answer the other possible advantages of laser based generation are due to the mechanism in which lasers produce ultrasound. As the material under test acts as the 'transducer' all wave modes supported by the material are generated, as opposed to a piezoelectric transducer which relies on mechanical energy to induce ultrasonic waves in the sample, and thus relies on angled incidences to generate the various wave modes. Lasers also produce surface (Rayleigh) waves very efficiently when compared to piezoelectric probes.
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In some of the ultrasonic nondestructive damage evaluation of solids, why receiving probes having twice the frequency of transmitting probes are used ? What will be the drawback if both the probes have same frequencies ?
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Not sure this is the case in your application, but some types of damage give rise to significant non-linear behavior, causing higher harmonics in the received signal. Thus the presence of higher harmonics (particularly at twice the excitation frequency) is sometimes used as an indicator for damage. If your measurement is based on this effect it makes sense to choose the receiving probe to have twice the frequency of the transmitter.
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I need a system to monitoring in real time the scaling formation of CaCO3 in a stainless steel piping, I have been studying about the acoustic emission techniques, can anyone confirm this? Or give an advice about any other NDT to do the same work?
Greetings.
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I would approach the problem with a circumferential lamb wave.  This can be easily monitored continuously with a pair of EMATs which could measure the build up over time as a change in both attenuation and transit time.  The measurement would be easy and robust.  Calibration of thickness would require some measure of the physical properties of the scale, density, stiffness(modulus), or simply some experience or equivalent calibration specimens.  The EMAT could operate at high temperatures and will not degrade in time like a piezo with adhesive.  I have done similar measurements in Inconel (Ni alloy).  Contact me for more information. ralers@rosen-group.com
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I would like to know about existing and effective methods for qualitative NDT evaluation of the hidden interface between two materials: e.g. the interface between fibers embedded in organic-based or inorganic-based matrices.
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So far I can think of no method not yet cited.
You definitely must have a closer look to thermal imaging, but in your case with vibroacoustic stimulation (by a sonotrode). I would not be so sure that pulse thermography will not give results, but you will have to choose carefully the source.
Ultrasonic methods by transmission methods may (or may not!) work. It is worth a try with rather low frequencies transducers.
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I would like to know the experimental procedure to measure the HVL in these linacs.
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Marcelino I figured you would know the docs, I have only seen linatrons in the paperwork but had a colleague who repaired then for Varian at a govt munitions factory. I could understand the addition of the steel plate to harden the beam since it would rid the beam of a lot of the low energy and make imaging a whole lot easier. In fact on one of the data sheets Varian show a beam flattening filter which of course would not only improve the beam shape but also harden the beam. I know in the medical world the Varian flattening filter free linacs still have a insert in the beam line to "rid the beam of low energy". Cheers
Lindsay
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I know the definition of signal strength but confused about the physical meaning. When do we need it? Why do we need it? and so on. 
Thanks in advance.
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It could mean two facts: how strong the fracture (atomic breakage) is, i.e. the source strength, and how close the fracture is located to your AE sensor, i.e. the geometric attenuation. The former is the characteristic of your material while the latter is of the relative location between the source and the sensor. The AE in the form of bulk elastic wave decays at the rate of 1/distance of propagation. Hope this helps. 
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I am working on a research for NDT selection and I am looking forward to make a crack in the sample, preferably without using impactor.
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Hello! Firstly, although it has been a very long time, thank you for your response! I got caught up with the research and , afterwards, my studies, and completely forgot to answer. Unfortunately it was decided that due to the boundaries of the project no crack  is going to be introduced. We only introduced inclusions.
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Hello everyone, I am trying to set up a "nondestructive testing lab" for casting metal. Please suggest any nondestructive testing equipment. If possible, then send me the supplier address.
Thank You.
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NDT methods can be roughly classified in two groups: surface techniques, which are used to identify surface and near surface defects such as cracks and surface porosity, and sub-surface techniques, that can be used to detect defects that lie under the material’s surface. In the first group, the most commonly used techniques are visual and optical testing, magnetic particle testing, liquid penetrant testing and electromagnetic testing. On the other hand, sub-surface techniques include radiography and ultrasonic testing among the most used.
Aside from the aforementioned techniques, which account for well over 90 per cent of the industrial NDT, there is a number of alternative methods each at different levels of technology readiness, such as thermography testing, process compensated resonance testing (PCRT), holography, shearography, alternating current field measurement (ACFM), and laser ultrasound.
A comprehensive description of the principles and applications of at least the classical NDT methods can be found in this reference: S. Ness, C. N. Sherlock, P. O. Moore, and P. McIntire. Nondestructive testing overview. American Society for Nondestructive Testing, 1996.
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I created a model for a coil located over a conductor, coil is a multiturn coil with driving current of 1 amper. I modeled the half of geometry and the quarter of geometry. By decreasing the geometry from half to quarter the coil inductance value is getting half but this does not happen for the coil resistance. In fact I get a wrong value for the resistance of the coil. Could anybody take a look at these models and help me to find the mistake?
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Hi Ehsan,
Thanks for the link to the comsol blog on the use of symmetry which I read with interest. This actually confirms what I thought might be happening. From what is described in the blog, the multi-turn coil feature in comsol appears to use what is usually called the 'current sheet' approximation. This replaces the current flowing through the multi-turn coil with a uniform current sheet that flows around the coil perimeter. This is an approximation which, once in place, permits the use of symmetry as a means to reduce the model size.
However, this approximation is only good for tightly wound coils and only for estimating the coil's inductance. The reason is that the inductance is primarily determined by the magnetic flux external to the coil (giving rise to the external inductance) which depends on the total current flowing in the wire. Therefore, using a uniform current sheet doesn't alter the result for the inductance too much from that obtained using the actual coil geometry.
However, the internal inductance (that due to the magnetic flux inside the wire) and - most importantly for what you are looking at - the coil's resistance will not be accurately determined by the current sheet approximation.
To get an accurate simulation of the resistance, the spatial distribution of current in the actual wire geometry must be detemined. In an isolated single turn of circular wire, this distribution of current will be cylindrically symmetric and follow the same kind of distibution as the electric field, that is, it will be concentrated near the surface of the wire and decay exponentially into the wire - the familiar 'skin effect'.
When additional turns of wire are added and brought close together (as in a tightly wound coil) the current distribution in the wire will be altered due to the 'proximity effect' which results from the Lorentz Force on the electrons in the wire due to the magnetic field in neighbouring parts of the coil. The net result is that the current gets concentrated in the parts of the wire cross section that are nearest to the other turns. The current is then no longer cylindrically symmetric within each turn of wire. This proximity effect therefore increases the resistance over and above that due to the skin effect since the current now flows in a reduced cross sectional area.
The proximity effect isn't modelled by the current sheet approximation. Therefore, one cannot utilise symmetry in the comsol multi-turn coil model for calculating resistance (or internal inductance).  A real multi-turn coil doesn't have symmetry with regard to the actual current distribution in the wire.
Regards,
Ray
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I've read some papers on magnetic Barkhausen effect. In all these papers, low frequency sine wave or triangular wave is used as excitation. Can magnetic Barkhausen effect occur under square wave exitation?
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Actually, it is possible but using broadband signals makes it harder to detect the BN; but it is possible!
J. Appl. Phys. 73 (lo), 15 May 1993
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I am planning to start working on this subject
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Ground penetrating radar (GPR) is a nondestructive geophysical method that produces a continuous cross-sectional profile or record of subsurface features, without drilling, probing, or digging. The GPR cross-section shows the ground surface at the top of the profile, and the reflections of subsurface geologic units and objects to a certain depth at the bottom.
Ground penetrating radar operates by transmitting pulses of ultra high frequency radio waves (microwave electromagnetic energy) down into the ground through a transducer (also called an antenna).
Ground penetrating radar (GPR) can be used in scanning of primarily concrete specimens to locate rebar, pipes, post tension bars, conduits in concrete structures and even cracks/anomaly in the concrete specimen . The scanning can also detect voids within concrete slabs and under concrete slabs. I hope the same can be used in your case.
I have been working with GPR on concrete and it has given be satisfactory and desired results. I think you can try using this device with ceramics as well. Hope this answer helps. 
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Give me the list of nondestructive test used for "thin film with substrate" for characterization. Thank you.
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It depends on what you are looking for:
There are different non-destructive tests that gives different properties of thin films.
1. Profilometer for film thickness. 
2. AFM or SPM (scanning probe microscopy) for surface topography.
3. Four point probe Sheet Resistivity or non contact mode sheet resistance measurement setup for electrical properties.
4. XRD crystal structure and for stress measurement in thin films.  
5. SEM, TEM .
6. XRF for elemental/chemical analysis.
7. UV-VIS spectroscopy for optical properties like transmission and for semi-conducting properties like band gap determination.
There are plenty of more techniques which are available in literature, but it would depend on what kind of property you are looking for.
There are several destructive techniques as well.
1. Like scratch test for adhesion measurement.
2. Nano Indentation for hardness and elasticity.
etc.
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White noise excitation for frequency response of ultrasound Ttransducer.
My present method consists in (for transducer working a center frequency f):
1. Modulate a sine with white noise.
2. Send signal with emitter.
3. Receive signal with receiver.
4. Acquire reception.
5. Demodulate with sine.
6. Remain with only the white noise response which is h(t) of the transducer.
This would be used to characterize the transducer. Is there anything wrong with this approach? And if so, what step should be added/removed. Feedback required.
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The standard and easier methodology for obtaining the frequency response of an ultrasound transducer is to drive it with a very short-time electrical pulse (spike), typically with a duration minor that -a quarter of the wavelength al the nominal tranducer frequency-, and then to see its echo-response (from a parallel reflector) in a oscilloscope. Finally, to make the FFT transform of the echo pulse properly windowed. 
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I am working on using non-linear ultrasonic parameters, specifically, the ratio of the amplitude of the secondary harmonic to the fundamental to quantify creep damage in austenitic stainless steel.
I have a couple of questions about the results, like the peaks I see in the waveform, etc.
It would be of great help and interest if somebody knows about this particular application of ultrasonic testing.
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Jitendra, 
I have read your papers. It is a huge part of my PhD thesis, the concept of NLU and your work is the main inspiration. One of the first papers I read. 
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The use of vibrating strain gages is rather common to monitor the deformation of large dams, nuclear containments, bridges, tunnels and so on. These gages are embedded in concrete structure and are known to have a good performance in terms of accuracy and lifetime. I have found an article in French (http://www.barrages-cfbr.eu/IMG/pdf/col2012-2-06-auscultation_par_capteurs_a_corde_vibrante-rex.pdf) dealing with West European practice. Is there any other industrial feedback available, from other parts of the world for instance?
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Thank you for your reply. It looks interesting, indeed. I sent you a request for a full text version, I would like to learn more about your topic. Thanks again.
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This question is put just to launch a kind of opinion poll over scientist or engineers. In fact, even people who are non-specialists in the sensing systems or in SHM but who are likely to use monitoring outputs for their usual business (numerical simulations, structural analysis). My point of view is that this technique is promising with a high level potential of use but it needs more industrial experiences to be implemented as an industrial scale, such as "traditional" sensors.
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I think that fibre optic sensors have a potential to be used on industial scale in construction engineering. They allow for continuous, real-time monitoring of structural beahviour which finds application in responsible structures, such as bridges. Because of their shape and reltively small dimensions optical fibres can be easily introduced into linear structural elements such as strands and cables. This is happening right now. In future fibre optics are considered to be a major component of the so-called smart structures - structural elements which serve both structural and monitoring functions. Fibre optics glued or woven into the fibrous structure of such a smart element will allow for colection of data about behavior of the structural element (deformations and strains).
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I am looking for a wavelength region which shows good correlation with pigment and colour of fruit crops while developing a multivariate calibration model using NIR spectra. Could anybody tell me what sort of algorithm and software I could use to find the right wavelength region?
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Variable selection procedures such as genetic algorithms or interval partial least squares procedures are useful when developing your models. Once you have a model you should test the predictive ability with independent test sets and inspect the selectivity ratios of the selected variables. An alternative to selectivity ratios are variable importance to projection scores (VIP). You should be able to do this in Unscrambler (but it's been a very long time since I used this). Matlab and PLS toolbox are my recommendations.
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I use a dual-transducer configuration (emitter and reception), and I would like to estimate the response of a steel block that contains multiple scatterers (error echoes). I would like to get an estimate of the response of the block in the absence of defects. Note: I use pseudo-chirp excitation signals (pseudo-linear FM).
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We have Ultrasonic method with conventional devices and phased array devices.
In case we use a conventional device:
the most common technique (estimation method) is Pulse Echo technique.
This technique enables the inspector to have a detail depiction of the metalic structure with one probe. If we look weldings then we need definetely probes of 45 angle, 60 angle and 70 angle. We also need a zero( or 90) angle probe to inspect the metal base.
In all other cases we use only a zero( or 90) probe. We have to be
careful with the metal because each metal has a different velocity in longitudinal and transverse wave. For instance the aluminum has approximately 3.130 m/sec velocity in transverse wave but 6.230 m/sec velocity in longitudinal wave, when the steel has 3.250 m/sec velocity in transverse wave but 5.920 m/sec velocity in longitudinal wave.
If we are able to inspect only from one side of the sample, then we choose dual probes.
An other technique is named TOFD and we need two probes which are placed in a distance between them, but with this technique we can not have an estimation about the characteristics of a possible discontinuity.
Sincerely
N. Poulakis
Tech. Educ. Inst. of W. Macedonia, Kozani, Greece.
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EM noise is present due to other equipment.
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Normally I use digital FIR filter for guided waves in general. In my case I work with Burst excitation and it is necessary to filter the signal. Also it is possible to use average process to decrece noise
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Ultrasound is inherently band-limited thus limiting the temporal resolution of the system. Spectral extrapolation, coupled with deconvolution can improve the lack of resolution. I'm attempting to compare the Yule-Walker algorithm to Berg's method and the Levinson-Durbin algorithm for stability and accuracy.
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@Imran Shafi - It is not that I didn't like it. Actually I haven't read it, It is just that I think one should not advertise his/her own research this way. Publish it, go to conferences and present it and let readers and listeners decide :-)