Papers by Eduardo Moreno Hernandez
It is well known the use of ultrasonic waves in weld testing. The most popular ultrasonic techniq... more It is well known the use of ultrasonic waves in weld testing. The most popular ultrasonic techniques are the transversal waves with a single transducer and longitudinal waves for the case of TOFD. One alternative is theuse of fundamental Lamb waves with the advantage that they can be used far from the weld. However, the lowfrequencies associated with these fundamental modesare not suitable for high resolution testing. In this paper the use of overtones modes in weld testing, with high phase velocities were studied. A phase velocity method wasused to identify the different Lamb mode echoes obtained from edges, weld and a notch in a 5 mm thickness plate.
Revista Mexicana De Fisica - REV MEX FIS, 2003
Recibido el 30 de julio de 2002; aceptado el 9 de abril de 2003 Acoustic pressure fields generate... more Recibido el 30 de julio de 2002; aceptado el 9 de abril de 2003 Acoustic pressure fields generated by pulsed ultrasonic transducers under different boundary conditions are analyzed. Numerical simulations of the near-field pressure were evaluated considering rigid and soft baffles as boundary conditions. These field simulations were perfomed using the temporal convolution between the numerical derivative of the impulse response and the longitudinal wave velocity for both cases. Experimental pressure data were obtained by measuring the peak, peak to peak and root mean squared voltages. Simulated and experimental results were compared to investigate the temporal behavior of the acoustic signal as well as their spatial distribution on planes parallel to the transducer face. Special attention is given to the Fresnel region where the diffraction effect affects the pressure field measurements. Experimental readings were done using circular transducers with the same geometric characteristics and with resonant frequencies of 3.5 MHz and 5 MHz.
Lecture Notes in Computer Science, 2005
Defect detection by ultrasonic method is limited by the pulse width. Resolution can be improved t... more Defect detection by ultrasonic method is limited by the pulse width. Resolution can be improved through a deconvolution process with a priori information of the pulse or by its estimation. In this paper a regularization of the Wiener filter using wavelet shrinkage is presented for the estimation of the reflectivity function. The final result shows an improved signal to noise ratio with better axial resolution.
2013 Pan American Health Care Exchanges (PAHCE), 2013
ABSTRACT Segments of vessels from the own patient, as saphenous vein or mammary or radial arterie... more ABSTRACT Segments of vessels from the own patient, as saphenous vein or mammary or radial arteries, are used to make coronary bypasses. The most effective technique, employed to evaluate the quality of these vessel, prior to their implantation into the periphery of the heart is the so called ultrasonic transit time flowemeter (TTFM). Some improvements in that technology still must be made to extract its full potential in order to achieve reliably measurements of very small blood flows in narrow lumen arteries and veins. In this paper, we present a software program, specifically developed to facilitate the surgical work of the surgeons, providing additional facilities for a quantitative dynamic visualization of flows in the implants during the surgical process. The flow-meter equipment integrates a TTFM analog-digital system, PC-compatible and with FPGA control, developed in a multilateral project funded by CYTED. The system is portable, low cost, robust, and easy to be used.
Ultrasonics, 1998
ELSEVIER Ultrasonics 35 (l 998) 581586 Thickness measurement in composite materials using Lamb wa... more ELSEVIER Ultrasonics 35 (l 998) 581586 Thickness measurement in composite materials using Lamb waves Eduardo Moreno a, Pedro Acevedo b'* a Centra de Ultrasonica, JCIMAF, CITMA, Calle 15 No. 551, Vedado, La Habana, 10 400, Cuba b DEAIIMASUNAM, Apdo. ...
Ultrasonics, 2003
Scope of the Journal The Turkish Journal of Electrical Engineering & Computer Sciences is publish... more Scope of the Journal The Turkish Journal of Electrical Engineering & Computer Sciences is published electronically 6 times a year by the Scientific and Technological Research Council of Turkey (TÜBİTAK) and it accepts English-language manuscripts in the areas of power and energy, environmental sustainability and energy efficiency, electronics, industry applications, control systems, information and systems, applied electromagnetics, communications, signal and image processing, biomedical engineering, biometrics, object recognition, classification, feature extraction, parallel and distributed computing, cognitive systems, interaction, robotics, digital libraries and content, personalized healthcare, information and communications technology, sensors, and artificial intelligence. Contribution is open to researchers of all nationalities. Publication Policy Open Access and Free Submission Statement TÜBİTAK academic journals are open access journals-all the manuscripts published in these journals are freely available online for anyone. There are no subscription or submission charges. All of our academic journals operate under the Creative Commons Attribution license in International Version 4 (CC BY 4.0). This allows for the reproduction of articles free of charge with the appropriate citation information. All authors publishing with TÜBİTAK academic journals accept these as the terms of publication.
Japanese Journal of Applied Physics, 2008
Piezoelectric arrays with different connectivities are widely used in actuators, transformers, an... more Piezoelectric arrays with different connectivities are widely used in actuators, transformers, and special ultrasonic transducers. In this study, the global matrix method is presented to describe the resonance radial modes in thin piezoelectric annular arrays with an arbitrary number of elements. Each annular element of the arrays is modeled as a three-port system with one electrical and two mechanical ports.
Japanese Journal of Applied Physics, 2007
In this article, we present a feasibility study using transducer edge waves to center a hydrophon... more In this article, we present a feasibility study using transducer edge waves to center a hydrophone during field characterization. A mathematical analysis is presented to study amplitude changes in edge waves; this analysis is based on the impulse response method and considers the transducer as a piston embedded in a rigid planar baffle. The experimental setup used to measure the edge waves is also presented. It has been observed, mathematically and experimentally, that edge wave amplitude reaches its maximum when the hydrophone is centered and that these amplitude changes are very sensitive to position, approximately 70% of its maximal amplitude; however, amplitude changes in front planar waves are less evident (10%). Agreement between experimental and calculated results demonstrates that changes in edge wave amplitude can be used to center the hydrophone in an objective way.
Acoustical Imaging, 2004
In medical application, ultrasound is extensively used as a diagnostic tool. There is a wide rang... more In medical application, ultrasound is extensively used as a diagnostic tool. There is a wide range of medical instruments which are used in this field from simple fetal phones to very sophisticated imaging systems. The main advantage of ultrasound when applied to diagnostic is that it is non-invasive. In Cardiology, the ultrasonic Doppler detector is a very useful instrument to monitor blood flow, this detector measures the blood velocity in veins and arteries. These measurements provide information about the presence of stenosis and obstruction in arteries. Stenosis is a disease that affects blood flow velocity and pressure producing turbulence, due to this the velocity profile changes modifying the frequency spectrum of the signal, these changes determine the stenosis level.
2011 Pan American Health Care Exchanges, 2011
HOOR SHUPLWLy PLQLPL]DU VX FRVWR \ VX WDPDxR 7DPELpQ VH SUHVHQWD XQ QXHYR VRIWZDUH TXH EULQGD XQD... more HOOR SHUPLWLy PLQLPL]DU VX FRVWR \ VX WDPDxR 7DPELpQ VH SUHVHQWD XQ QXHYR VRIWZDUH TXH EULQGD XQDV LQWHUHVDQWHV IDFLOLGDGHV GH RSHUDFLyQ OR TXH UHVXOWD LQGLV SHQVDEOH SDUD XQ PDQHMR UiSLGR \ VHQFLOOR HQ TXLUyIDQR SRU SDUWH GHO FLUXMDQR HQ VLWXDFLRQHV D YHFHV GLItFLOHV (O FRQMXQ WR RIUHFH XQ VLVWHPD HFRQyPLFR UREXVWR \ GH IiFLO PDQHMR ISBN: 978-1-61284-918-8 IEEE Catalog Number: CFP1118G-ART
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Papers by Eduardo Moreno Hernandez