A Texas instruments DSP-based acoustic source direction finder

This document describes the implementation of a DSP-based acoustic source direction finder and its application to control the direction of a steerable camera. For real-time implementation a TMS320F2812 digital signal controller was used. The system can be used for different applications like in teleconferencing rooms or surveillance systems. This report presents a description of the developed system in three phases of the project: direction of arrival estimation, analog interfase, and servomotor control. The application was developed by undergraduate students at the Autonomous University of Zacatecas as a final project in the course “DSPs programming”, which is one of the DSP courses thought in the Communications and Electronics Engineering program, with a major in DSP

Image Addition by Computer Generated Multiplexed Holograms

A new approach to perform image addition via computer generated multiplexed holograms is described. The purpose of this work is to handle flat objects that are to be stored in a hologram. When holograms are reconstructed, images appear simultaneously in the same direction and same diffraction order, thus recovering a more complex image. The experimental results demonstrate the suggested procedure

Image restoration a comparative study of some methods applied to color images

The present work introduces five different methods to deal with digital image restoration. Particularly deconvolution by Richardson-Lucy method, Wiener filter, deconvolution with Gaussian priors in the frequency domain, spatial domain and the use of sparse priors. The Bayesian methodology is based on the prior knowledge of some information that allows an efficient modeling of the image acquisition process. The edge preservation of objects into the image while smoothing noise is necessary for an adequate model. Thus, we use five deconvolution methods to recover images, all of the presented images are contained on TID 2008, all of them were previously degraded by Gaussian noise and convolved with a disc point spread function (PSF) making reference to a typical fluorescence microscopy degradation. The principal objective when using restoration methods in the context of image processing is to eliminate those effects caused by the excessive smoothness on the reconstruction process of an image which is rich in contours or edges and also is important to consider the process time due to an improvement in this área could lead to a faster application. A comparison between the five methods is presented for a restoration process. This collection of implemented methods has been compared using different metrics such as SNR, PSNR, SSIM and process time. The obtained results showed a satisfactory performance and the effectiveness of the proposed methods on color space

Teaching digital holography through an interface in Java

We present an interactive simulation software to help to teach and learn the holography concept. The education interface was developed in the Java platform. The Holographic Interface is a computer assisted learning that can be used in classrooms or for distance education. The binary holograms are numerically generated and reconstructed in the virtual optical laboratory. Several procedures are shown. The interface has been implemented with different options such as addition, subtraction, multiplexing and some properties of holography. Moreover, the software was designed to simultaneously visualize the 2D object, the generated hologram and the recovered image. We have taken into account the students’ suggestions in this version in Java

Measurements of concentration differences between liquid mixtures using digital holographic interferometry

We present an alternative method to detect and measure the concentration changes in liquid solutions. The method uses Digital Holographic Interferometry (DHI) and is based on measuring refractive index variations. The first hologram is recorded when a wavefront from light comes across an ordinary cylindrical glass container filled with a liquid solution. The second hologram is recorded after slight changing the liquid’s concentration. Differences in phase obtained from the correlation of the first hologram with the second one provide information about the refractive index variation, which is directly related to the changes in physical properties related to the concentration. The method can be used − with high sensitivity, accuracy, and speed − either to detect adulterations or to measure a slight change of concentration in the order of 0.001 moles which is equivalent to a difference of 0.003 g of sodium chloride in solutions. The method also enables to measure and calculate the phase difference among each pixel of two samples. This makes it possible to generate a global measurement of the phase difference of the entire sensed region

Evaluación de la eficiencia de un calentador solar de tubos evacuados implementado con una tarjeta Arduino Mega

El siguiente documento presenta el rendimiento térmico obtenido de un sistema de calentamiento de agua de tubos evacuados; caracterizado y evaluado en el Campus Universitario Siglo XXI de la Universidad Autónoma de Zacatecas. Donde se refleja la evaluación del sistema operando dinámicamente, con el objetivo de describir la existencia de afecciones por nubosidad y mala estratificación del fluido las cuales provocan la caída de la eficiencia del colector. Por ende al obtener las curvas de operación del sistema y realizar un ajuste lineal, se observan que las afecciones provocadas por la nubosidad y la estratificación deficiente del fluido al iniciar la operación del sistema por la mañana, limitan considerablemente el calentamiento del agua de una forma eficaz

A reduced search algorithm for speaker recognition

In this work, a reduced search algorithm for vector quantization codebooks is applied as a way to reduce the risk of wrong decisions in an automatic speaker recognition system. Instead of a full search method, the algorithm is based on the geometrical properties of the vector space, reducing the search to those codebooks which are closer to the vector under test. The speaker recognition system is intended to identify a suspect, between a small group of persons, using low quality recordings, working as a text independent automatic speaker recognition system. It was found that the alternative search algorithm can be used to reduce the risk of wrong decisions, which is specially important in forensic applications

Obtención de la respuesta en frecuencia auditiva usando un modelo bio-mimético

Se propone un modelo matemático con relación a la posición en el espacio de una fuente de sonido. El modelo matemático es función de los ángulos de azimut y elevación, partiendo de la medición de la Respuesta en Frecuencia Relativa a la Cabeza (HRTF) en un modelo bio-mimético. El modelo bio-mimético se construye con base en un maniquí (cabeza) que simula a una persona a la cual se le hacen incidir ondas sonoras desde diferentes posiciones en un espacio radial. Se observó que la posición de los polos y ceros del modelo matemático pueden dar información de la localización de la fuente

Real-time measurement of the average temperature profiles in liquid cooling using digital holographic interferometry

We present an alternative optical method to estimate the temperature during the cooling process of a liquid using digital holographic interferometry (DHI). We make use of phase variations that are linked to variations in the refractive index and the temperature property of a liquid. In DHI, a hologram is first recorded using an object beam scattered from a rectangular container with a liquid at a certain reference temperature. A second hologram is then recorded when the temperature is decreased slightly. A phase difference between the two holograms indicates a temperature variation, and it is possible to obtain the temperature value at each small point of the sensed optical field. The relative phase map between the two object states is obtained simply and quickly through Fourier-transform method. Our experimental results reveal that the temperature values measured using this method and those obtained with a thermometer are consistent. We additionally show that it is possible to analyze the heat-loss process of a liquid sample in dynamic events using DHI. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE

Obtención de la respuesta en frecuencia auditiva usando un modelo bio-mimético

Se propone un modelo matemático con relación a la posición en el espacio de una fuente de sonido. El modelo matemático es función de los ángulos de azimut y elevación, partiendo de la medición de la Respuesta en Frecuencia Relativa a la Cabeza (HRTF) en un modelo bio-mimético. El modelo bio-mimético se construye con base en un maniquí (cabeza) que simula a una persona a la cual se le hacen incidir ondas sonoras desde diferentes posiciones en un espacio radial. Se observó que la posición de los polos y ceros del modelo matemático pueden dar información de la localización de la fuente