Arturo Vera - Academia.edu (original) (raw)

Papers by Arturo Vera

International Journal of Pediatric Otorhinolaryngology, 2011

Objective: To study the development of the stapedius muscle canal in human embryos and foetuses. ... more Objective: To study the development of the stapedius muscle canal in human embryos and foetuses. Materials and methods: 46 temporal bones with ages between 9 mm and new-borns were studied. The preparations were dyed using Martins' trichrome technique. Results: Two areas of different embryological origin form the stapedius muscle canal, which contains this muscle and the facial nerve. On the otic capsule, at 11 weeks an extension starts to grow from its caudal part, which moves outwards and near to Reichert's cartilage, forming the footplate and internal wall. The pyramidal eminence comes from the mesenchyme that surrounds the muscle, forming a partition to separate it from the laterohyale portion of Reichert's cartilage.

Scanning, 2006

The degradation of electrolytic tinplate used in food containers was analysed and evaluated, usin... more The degradation of electrolytic tinplate used in food containers was analysed and evaluated, using scanning electron microscopy and electrochemical measurements of microcorrosion and ion dissolution by atomic absorption to prevent food contamination caused by metal traces and to increase the durability of such tinplates.

This paper describes an applicator of electromagnetic fields for its clinical use in oncology hyp... more This paper describes an applicator of electromagnetic fields for its clinical use in oncology hyperthermia treatments. The applicator is a rectangular waveguide working at 200 MHz. In order to reduce the applicator dimensions (8.5 cmtimes4.2 cmtimes16.9 cm), it was filled with deionized water. After designing the applicator, it was characterized for its clinical use. Electric field distribution, impedance, and calorimetric measurements are presented in this paper

Japanese Journal of Applied Physics, 2006

An accurate and noninvasive temperature measurement inside phantoms and tissues is important to i... more An accurate and noninvasive temperature measurement inside phantoms and tissues is important to improve hyperthermia treatment. The use of ultrasonic echo-pulses for this purpose is a promising line of research. In this paper, we propose an alternative method for processing echo-signals received from inner regions in phantoms. Ultrasonic estimation of temperature is carried out using a phase demodulation technique, which gauges the indirect effects in the phase domain of the previously reported time-shifts in the echo position. The potential performance and high sensitivity of this procedure is explained and verified with several simulated examples. Finally, the proposed procedure is applied to the experimental assessment of phase changes with temperature in ultrasonic echoes successively acquired from different milieus. In all cases, the results show good performance and high sensitivity. This is an interesting alternative to measurements in waveforms of the very small delays (nanoseconds) associated with this ultrasonic temperature estimation.

IEEE Internet Computing, 2010

ABSTRACT In ultrasonic physiotherapy, the therapeutic effect is produced in the first 5 cm, into ... more ABSTRACT In ultrasonic physiotherapy, the therapeutic effect is produced in the first 5 cm, into the Fresnel zone. Models are focused principally in the Fraunhofer zone which is too far from the therapeutic region. More realistic models are required to express the overlapping commonly produced near the transducer face. This paper presents the modeling of the acoustic field of physiotherapy ultrasonic transducers under non-uniform pressure distributions by using the finite element method. Theoretical approaches are compared with measurements to determine their accuracy. Although the nonuniform vibration models were presented years ago, their validation is still not complete. The results show the efficacy of modeling real transducers under free vibrating, simply supported and clamped conditions in relation to the overlapping in the Fresnel zone. In was concluded that the Fresnel zone is not correctly modeled with any of the approaches of this paper which were proposed in the literature.

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.

The state of the art and already on market electromechanical prosthesis are mostly implemented by... more The state of the art and already on market electromechanical prosthesis are mostly implemented by using the sequential movement of actuators, which give extra load to each other during movement. As a solution to this problem, some of the newest prosthesis (mostly in development) use simultaneous movement of actuators instead, which increase their overall load capacity and their DOF. However, backbones of mostly newest electromechanical prosthetics are microcontrollers, which are sequential by nature. Therefore, implementing simultaneous movement of actuators using sequential systems is not an easy task to do. In this article, we propose a simultaneous control logic based on interrupts. Proposed implementation performance is then being tested by using an electromechanical arm prosthesis of 3 DOF developed at CINVESTAV Mexico. Proposed testing bench uses brushless DC servomotors as actuators, a 16-bit architecture platform, and standard C modular coding for embedded systems. At the end of this article, we account, summarize and discuss about movement effectiveness of the proposed testing bench.

In this work, advanced digital design techniques are used to implement the generation of signals ... more In this work, advanced digital design techniques are used to implement the generation of signals for control and synchronism of an ultrasonic system employed in the flow detection technique known as Transit Time Flow Measurement (TTFM), for the estimation of blood flow in coronary revascularization surgeries. The control logic is implemented using hardware description language and it gives the system reconfigurable features in real-time. Its design is verified and finally, the Intellectual Property Module is obtained. Then, an ultrasonic embedded system to measure blood flow in vessels can be obtained. This work is part of the CYTED multinational project "Ultrasonic and Computational Systems for Cardiovascular Diagnostics" (SUCoDiC), the first Consortium Project of the Ibero-American Program CYTED.

$Research paper thumbnail of Field induced piezoelectric transducer for generation of controlled diffraction ultrasonic field$

In this work, ultrasonic transducers were developed using relaxor ferroelectric ceramics based on... more In this work, ultrasonic transducers were developed using relaxor ferroelectric ceramics based on modified-lead magnesium niobate lead titanate ceramics (PMN-PT). It was found that PMN-PT ceramics present large field-induced electromechanical coupling factors, high piezoelectric anisotropy (k t /k p >>1) and relative high mechanical quality factor at relatively low DC bias field. Thus, "Bessel-like" transducer, which was composed of three concentric electrodes, based on PMN-PT relaxor ceramics was developed and its acoustic radiation field for different levels of electric field-induced piezoelectric response was mapped. The experimental results revealed that the acoustic field may be significantly modulated by adjusting the DC bias field. The results obtained for this tunable "Bessel-like" transducer are compared with those obtained for similar based on PZT ceramics.

In this article, it will be described the state of the art of upper limb prosthesis and several t... more In this article, it will be described the state of the art of upper limb prosthesis and several types of them. The prosthesis evolution had allowed people who lost an extremity to win back their normal life and live it with fewer limitations. Designing a myoelectric prosthetic arm that interacts with the amputee requires the integration of countless disciplines. Traditional commercial prosthesis has at least three degrees of freedom: open and close the hook, bend and straighten the elbow and rotate the wrist; but the human arm has 22 degrees of freedom. Thus, it is important to realize that the prosthetics have a long way to go. Furthermore, the higher the amputation level, the greater the demands on the fitting technique. Each prosthesis has different characteristics, advantages and drawbacks. Finally, four different kind of prosthesis will be presented: the Boston Elbow, the Utah Arm, the Kuiken's Prosthesis within DARPA's Project and the prosthesis under development in our laboratory.

Thermal interstitial microwave ablation comparison between swine breast tissue and breast phantom... more Thermal interstitial microwave ablation comparison between swine breast tissue and breast phantom using a coaxial antenna was presented. Experimental protocol was composed by a radiation system and a thermometry system. Coaxial antenna works at 2.45 GHz, power apply during experiments was 10 watts for 5 minutes. Thermal sensors were placed next to the antenna, at 0.50 cm, 1 cm and 1.50 cm to the antenna. Data was stored every second in the course of microwave radiation. Thermal sensors next to the antenna present a mean variation of 0.48°C, at 0.50 cm to the antenna, average variation is 1.33°C, sensors placed at 1 cm have a mean temperature variation of 0.38°C, and finally average variation in sensors inserted at1.50 cm to the antenna is 0.09°C.

Gastroenterology, 2005

Page 1. A Microprocessor-Based System for Pulse-Echo Overlap Measurement of Ultrasonic Velocity D... more Page 1. A Microprocessor-Based System for Pulse-Echo Overlap Measurement of Ultrasonic Velocity Danny Rodríguez 1 , Antonio Jiménez 1 , Rubén Pérez 2 , Lorenzo Leija 2 , Arturo Vera 2 , Eduardo Moreno 1 . 1 Instituto de Cibernética, Matemática y Física (ICIMAF). ...

This paper presents a noise immunity analysis of time delay estimation (TDE) techniques used on u... more This paper presents a noise immunity analysis of time delay estimation (TDE) techniques used on ultrasonic echoes for non invasive temperature estimation. Four methods are analyzed. The methodology consists on corrupting a simulated ultrasonic signal (ideal signal) with white noise and a signal-to-noise ratio of 3dB and 6dB. After this, noise immunity analysis is performed for every method. The TDE techniques used in this work are Phase Difference, Phase Shift, Cross-Correlation and Quadrature Phase Demodulation. The purpose of this work is to determine the best method for non invasive temperature estimation.

This paper presents the modeling of the acoustic field of a physiotherapy ultrasonic transducer b... more This paper presents the modeling of the acoustic field of a physiotherapy ultrasonic transducer by using the finite element method. An ideal emission is presented obtained by using the approach developed by Rayleigh, called “piston in a baffle”. Simulations with FEM also are presented to compare them with the analytical results. The results of the model are also compared to those of the measurements in a physiotherapy transducer. The results show the efficacy of modeling the real transducers with ideal models in relation to the overlapping in the Fresnel zone and the characteristic parameters. A necessity is evident after this analysis: more appropriated models using more real boundary conditions. Results indicate that Fresnel zone is not correctly modeled using the ideal considerations.

An spectral analysis technique, that establishes a linear relation between the temperature change... more An spectral analysis technique, that establishes a linear relation between the temperature changes in a body and the frequency displacement in the overtone peaks being displayed in the power spectral density (PSD) of ultrasonic echo-signal, has been improved and applied by the paper authors to estimate temperature gradients induced inside a biological phantom by means of ultrasonic therapeutic radiation. In order to evaluate the technique results under controlled conditions, multi-pulse ideal waveforms are properly simulated, considering a non-linear temperature gradient as the thermal distribution induced on this simulated body. The results obtained by means of a very accurate spectral analysis are contrasted, at different depths, with the established increasing-decreasing temperature gradient. The adequacy of the technique to effectively estimate such a realistic temperature spatial distribution, inside a body, is evaluated regarding to selected frequency peaks behavior in comparison with thermal distribution along the central axis of the simulated body, under ultrasonic radiation.

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. The cored matrix model for radial modes, in a singular ring, is presented in the form of a translation matrix. The dynamic behavior of two annular arrays, a transformer and a Bessel transducer, is simulated assuming that the major surfaces of each element are stress-free, while the laterals are matched with neighbor elements. Thus, the inner and outer lateral surfaces of the system are loaded with an external medium. The simulated and experimental results are in good agreement when the thickness effects are neglected.

The aim of this work is the evaluation of a device for the ultrasonic propagation speed measureme... more The aim of this work is the evaluation of a device for the ultrasonic propagation speed measurement in biological tissues as well as its possible error sources during signal acquisition process. The proposed measurement system basically consists of an immersion transceiver, which was excited by a home-made pulser. The transducer radiates the interrogated material and a needles arrangement inserted in it. This arrangement generates a well defined echo pair. These echoes combine with the echoes generated in the characterized medium after they have been amplified. In the case of the measurement of the temperature dependence of ultrasonic propagation speed, the measurement system must be submerged inside a thermostatic bath which is capable of regulating the temperature within a 0.1°C resolution. The measurement of the distance between the needles that work as reflectors, and the vibrations caused by the hydraulic pump could generate artifacts in the acquired ultrasonic signals. These variations would induce error in the ultrasonic propagation speed measurements. A method to measure the distance between the reflector needles is proposed, and an evaluation of the effects of the vibrations as well as the advantages of using a fixed distance between the reflector needles is presented. The obtained results show that the thermostatic bath operation has effect on the ultrasonic signals; however, it could be neglected due to its minimal contribution in the propagation speed measurement. It is also proved that the needles arrangement is a good option to measure the propagation speed showing values near to the reported in degasified bidistilled water.

Physics Procedia, 2010

During hyperthermia treatments, for determining internal temperature by using non-invasive ultras... more During hyperthermia treatments, for determining internal temperature by using non-invasive ultrasound estimation, it is necessary to know some tissue ultrasonic characteristics around the hyperthermia range. The aim of this work was to determine in detail the changes of some ultrasonic properties (velocity and attenuation) of muscle, fat and liver tissues in the specific range of 26°C to 50°C. We proposed an experimental setup which allows minimizing the expansion effects in the biological samples. The ultrasonic signal passes through tissue and it is reflected by a 1-mm needle arrangement, inserted in the tissue sample. The results in the propagation speed behaviour, for the three studied tissues, appear to be quasi-linear with temperature changes. The attenuation coefficients are also presented for different temperatures.

Key Engineering Materials, 2007