Enrique Roldan - Academia.edu (original) (raw)
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Papers by Enrique Roldan
A crack in a thin plate reflects ultrasonic waves; therefore, it is reasonable to determine the l... more A crack in a thin plate reflects ultrasonic waves; therefore, it is reasonable to determine the location of the crack by measuring the reflected waves. The problem of locating the crack can be reformulated in purely geometric terms. Previously, time-consuming iterative numerical methods were used to solve the resulting geometric problem. In this paper, we show that explicit (and fast to compute) formulas can be used instead.
Se presenta algunos resultados del diseño e implementación de primitivas para KLM (Kernel for Sma... more Se presenta algunos resultados del diseño e implementación de primitivas para KLM (Kernel for Smal[L] Monitor), un sistema operativo básico, en tiempo real, que permite controlar los componentes de hardware y software de una microcomputadora basada en el procesador de señales digitales TMS320FC240. Dichas primitivas están escritas en C, y aquellas que dependen de su arquitectura de hardware, están escritas en su propio lenguaje. Las primitivas forman parte de un lenguaje de comandos que permiten la comunicación con una computadora anfitriona conectada a través de RS232. Estos comandos permiten explorar la memoria para escribir o leer datos. Asimismo, es posible leer o escribir puertos conectados a convertidores A/D, D/A, temporizadores, paralelos, seriales, entre otros. También es posible graficar las funciones programadas y modificarlas interactivamente si es necesario. Cabe mencionar que KLM fue desarrollado por uno de los autores (Peña) y alumnos en el Instituto Politécnico Nacional.
Smart Nondestructive Evaluation and Health Monitoring of Structural and Biological Systems II, 2003
This paper describes a Lamb-wave scanning method for the detection of notches simulating cracks a... more This paper describes a Lamb-wave scanning method for the detection of notches simulating cracks at rivet holes in thin plates. The approach requires the generation of an ultrasonic S o -Mode Lamb wave using an incident transmitter excited with a tone burst centered at a near non-dispersive frequency. Area scans are performed on a plate with a hole with a notch to generate times series information which is used to create animations illustrating the wave propagation characteristics. The time series are subject to a sifting process to obtain intrinsic mode functions which contain narrow frequency banded information of the signals. The Hilbert-Huang transform is applied to the intrinsic mode functions which permit the computation of the signal energy as a function of time, proportional to the square of the amplitude of the analytical signal. Animations of the propagation of the Lamb-wave energy illustrate that a potential scanning approach is to acquire time series along a line between the transmitter and the hole, capturing wave scattering from the hole and reflections from the notches. The times of flight and amplitudes of the notch-reflected energy are used to calculate coordinates of the source of the reflections by a geometric approach. The identified coordinates of the reflections outline the extent of the notch at the rivet hole. Results of experiments conducted on thin square plates with a single hole with notches of various sizes compare favorably with the actual notches.
Advanced Nondestructive Evaluation for Structural and Biological Health Monitoring, 2001
This paper describes work towards the development of a Lamb wave scanning method for the detectio... more This paper describes work towards the development of a Lamb wave scanning method for the detection of defects in thin plates. The approach requires the generation of an ultrasonic S0-Mode Lamb wave using an incident transmitter excited with a tone burst centered at a near non-dispersive frequency. A pair of receiving transducers, with a fixed relative separation, remotely scans line
A crack in a thin plate reflects ultrasonic waves; therefore, it is reasonable to determine the l... more A crack in a thin plate reflects ultrasonic waves; therefore, it is reasonable to determine the location of the crack by measuring the reflected waves. The problem of locating the crack can be reformulated in purely geometric terms. Previously, time-consuming iterative numerical methods were used to solve the resulting geometric problem. In this paper, we show that explicit (and fast to compute) formulas can be used instead.
Se presenta algunos resultados del diseño e implementación de primitivas para KLM (Kernel for Sma... more Se presenta algunos resultados del diseño e implementación de primitivas para KLM (Kernel for Smal[L] Monitor), un sistema operativo básico, en tiempo real, que permite controlar los componentes de hardware y software de una microcomputadora basada en el procesador de señales digitales TMS320FC240. Dichas primitivas están escritas en C, y aquellas que dependen de su arquitectura de hardware, están escritas en su propio lenguaje. Las primitivas forman parte de un lenguaje de comandos que permiten la comunicación con una computadora anfitriona conectada a través de RS232. Estos comandos permiten explorar la memoria para escribir o leer datos. Asimismo, es posible leer o escribir puertos conectados a convertidores A/D, D/A, temporizadores, paralelos, seriales, entre otros. También es posible graficar las funciones programadas y modificarlas interactivamente si es necesario. Cabe mencionar que KLM fue desarrollado por uno de los autores (Peña) y alumnos en el Instituto Politécnico Nacional.
Smart Nondestructive Evaluation and Health Monitoring of Structural and Biological Systems II, 2003
This paper describes a Lamb-wave scanning method for the detection of notches simulating cracks a... more This paper describes a Lamb-wave scanning method for the detection of notches simulating cracks at rivet holes in thin plates. The approach requires the generation of an ultrasonic S o -Mode Lamb wave using an incident transmitter excited with a tone burst centered at a near non-dispersive frequency. Area scans are performed on a plate with a hole with a notch to generate times series information which is used to create animations illustrating the wave propagation characteristics. The time series are subject to a sifting process to obtain intrinsic mode functions which contain narrow frequency banded information of the signals. The Hilbert-Huang transform is applied to the intrinsic mode functions which permit the computation of the signal energy as a function of time, proportional to the square of the amplitude of the analytical signal. Animations of the propagation of the Lamb-wave energy illustrate that a potential scanning approach is to acquire time series along a line between the transmitter and the hole, capturing wave scattering from the hole and reflections from the notches. The times of flight and amplitudes of the notch-reflected energy are used to calculate coordinates of the source of the reflections by a geometric approach. The identified coordinates of the reflections outline the extent of the notch at the rivet hole. Results of experiments conducted on thin square plates with a single hole with notches of various sizes compare favorably with the actual notches.
Advanced Nondestructive Evaluation for Structural and Biological Health Monitoring, 2001
This paper describes work towards the development of a Lamb wave scanning method for the detectio... more This paper describes work towards the development of a Lamb wave scanning method for the detection of defects in thin plates. The approach requires the generation of an ultrasonic S0-Mode Lamb wave using an incident transmitter excited with a tone burst centered at a near non-dispersive frequency. A pair of receiving transducers, with a fixed relative separation, remotely scans line