Research

Here is the place I'll try to keep updated with what I have been doing on academic grounds...



2009

missa do galo

I have made a bilingual version of the tale 'Missa do Galo' by Machado de Assis. It is available here.

2nd semester 2008

stress restoration effect

I have studied the stress restoration effect and applied its principle to investigate the effect of stress restoration, leading to the supposition that stress is supra-segmental and the restoration on this level may take place even though it fails to occur on the segmental level. Only a pilot project was made as a final work for the course on Stress ministered by professor Thais Cristofaro at UFMG. All the work was made considering the Portuguese language and the report (which may be download by clicking here) is also written in Portuguese. The presentation may also be download here. I hope to carry on this project and have an paper published in the near future.

cochlear implants and auditory models

During the course on speech science and technology we have presented a brief review on cochlear implants and auditory models. The presentation may be seen here. In order to contribute to a better world we made a bunch of updates on the Wikipedia entry for cochlear implants, only for the Portuguese version, which might be seen here.

doctoral project

My doctoral project is the application of Information Theory and Signal Detection Theory on the linguistics context, as a way to explain speech communication, its perception and observed effects.




1st semester 2008

anova

ANOVA stands for 'analysis of variance' which is a statistical test of hypothesis. It is used to verify if two given set of data come from the same distribution or not. Here is a short introduction written by myself in Portuguese.

working memory

Here is a short text I've written in Portuguese about working memory.

frequency and concreteness effect on visual word recognition

The effects of frequency and concreteness on written speech was studied as a final work for the course on Psycholinguistics by prof. Maria Luiza (UFMG). You can see the paper in Portuguese here.

Psycholinguistics

Here is a brief compilation (in Portuguese) of a few chapter from the book Psycholinguistics edited by Jearn Berko Gleason and Nan Berbstein Ratner.




2st semester 2007

watermark

As a part of the course on image detection and analysis I have done this work on watermarking. This one has an article (I hope I could improve it in order to get it published), which is written in English and a presentation in Portuguese.




1st semester 2007

orthographic projection

A presentation I prepared for a experimental class on orthographic projection. The presentation is in Portuguese and may be seen by clicking here.




2nd semester 2007 and 2nd semester 2005

Artificial Intelligence

I have gathered my notes, exercises and tests for my classes on Artificial Intelligence, they are all written in Portuguese and may be downloaded by clicking here.




old stuff

System identification using wavelets

This the theoretical part of the final work for the course on system identification. The paper here presented is written in Portuguese.

wavelets

A theoretical paper I've written about wavelets. It is in Portuguese and you may read it here.

Zur Farbenlehre

Presentation of the Theory of Colours Johann Wolfgang von Goethe. The work is available "here.

Dutch gender Painting from XVII Century and Johannes Vermeer

Final work for the course 'Art History'. The text is in Portuguese. For those interested, it is available here.

Flash Memory - Compact Cards

Flash Memory work by me and Lucio.

Microstrip

Microstrip is a plane transmission line. This work was made by me, Lucas and Felipe.

Finite Element Method in Acoustics

This is my final work for the course in Acoustics. It presents the Finite Element Method applied on Acoustics. There is here also a text I wrote on the subject.

Delaunay Triangulation

This is a presentation I gave with Lucas over the subject: delaunay triangulation.

Voronoi

A short presentation on Voronoi's Diagram, the Delaunay's Triangulation counterpart.

Die Zauberflote

Text about the Mozart's opera with some notes for vocabulary in Portuguese.

Dolby Digital Surround Sound (AC-3)

Here is a short introduction about the Dolby Digital Surround Sound (AC-3).

Digital Versatile Disk

Another shot introduction, this time about dvd.

Frans Post

See some of his paintings. And read about him on the article on Wikipedia which I have contributed.

hi8

A brief presentation about the hi8 format.

Image retrieval using color

A presentation based on the article 'A comparative study of several color models for color image invariant retrieval' by T. Gevers and A. W. M. Smeulders.

Face Recognition

Here is a presentation about the 'Wavelet packet analysis for face recognition' by C. Garcia, G. Zikos and G. Tziritas.

MPEG-7

It is presented here a short introduction on the mpeg7 standard.

Principles of Neuroscience

A presentation on Principles of Neuroscience, based on the book by Eric Kandel.

Hodgkin-Huxley Model

The Hodgkin-Huxley Model is a set of non-linear ordinary differential equations that approximate the electrical characteristics of excitable cells such as neurons. You may see here a short introduction I made about this topic.

Coincidence Detection on Octopus Cells

It is a work I carried during the LASCON 2006. You may download the presentation here.

Bionic Wavelet Transform

This is a presentation about Bionic Wavelet Transform: A New Time-Frequency Method Based on an Auditory Model.

Digital Filters

An incomplete text about digital filters.

Human Perception

An incomplete presentation (in Portuguese) about human perception.

wifi IEEE802.11

Final work on networks course, about IEEE802.11 standard.

Solitons

This is a text (in Portuguese) about solitons, which are special kind of waves that propagates with very low attenuation and dispersion, guaranteeing a that its shapes suffer lesser distortion. This was the final work for the course on optical communications.

Sound and Sensation

It is my presentation for the course in Psychoacoustics.

Music and Gestalt

A presentation on music and gestalt.

Why do octaves sound the same?

Trying to elucidate this subject through this presentation.

Real Networks

Back to the multimedia subject, here is a presentation about Real Networks.

Sony cameras

Another old presentation.

Cochlea Stimulation

Here are two simulations of cochlear stimulations. Simulation 1. Simulation 2.

wavelet toolbox for matlab

Some old functions for wavelet analysis I have coded a long time ago. You may download the zip file here.


published works

Master Thesis

Wavelet Filter Bank With Scaling Factor Larger Than Two (Portuguese)
abstract, pdf, presentation

The traditional wavelet analysis is equivalent to a filter bank, formed by a low-pass and a high-pass filter, in which the frequency resolution changes by one octave between two subsequent stages. In some applications, mainly in the one that inspired this work, i.e. modeling of the peripheral human auditory system, the frequency resolution of one octave is fairly poor (in human audition the frequency resolution is approximately of 1/3 of an octave) to attain a good representation of auditory phenomena. In the present work, it was chosen to particionate the subspaces using a scale factor greater then two and more than one wavelet, so that it is possible to achieve a better frequency resolution for certain bands. This change in the scale factor leads to the need to design new wavelets suited to the scale factor in use. In order to achieve this objective, a generalization of the wavelet construction proposed by Ingrid Daubechies, adapted to the situation in which the scale factor is not two anymore, is carried out. The results achieved show how to design the scale function and determine a property that the filter bank coefficients must satisfy in order to obtain a perfect reconstruction analysis filter bank. It is shown analytically and numerically that certain results achieved are indeed solutions. Nevertheless, it is still necessary to determine how to design the wavelet functions satisfying the imposed restriction and using the scale function desired.


Articles

A System for Multimodal Speech Reproduction (English)
abstract, pdf

It is described a program created for the production of realistic animations of tridimensional facial models in real time, based on LPC analysis of speech and previous determination of the characteristic dynamics of the speaker model. The final program was successfully able to render a model with 900 triangles in a frame with 350x400 pixels at 60 frames per second, driven only by parameters extracted from a speech signal.

A Brief History of Auditory Models (English)
abstract, pdf

This work presents a brief description of the human auditory system together with the history of human comprehension of the auditory function, its main features, and classic models used to represent it. First, a historical view of the hearing apparatus is presented. After that, the physiology of the peripheral auditory system is described. The process of acoustic propagation through the outer, middle and inner ear, as well as the mechanism of transformation of cochlea inner hair cell motion into neuron spikes are explained. Next, Flanagan’s mathematical representation (based on physiological data acquired by von Békésy) of the passive relation between the sound that reaches the outer ear and the motion of the cochlea basilar membrane. Flanagan’s model is followed by Lyon’s model of the cochlea, Meddis’ model of the inner hair cell, and Patterson’s Auditory Image Model. Finally, the IPEM Toolbox is introduced as an example of music analysis system that incorporates an auditory model to perform acoustic analysis of sound based on human perception.

Specialist System for Clarinet Timber Detection (Portuguese)
abstract, pdf

It is presented bellow a method for automatic identification of the clarinet. The schema described bellow is based on the analysis of the decomposed acoustic signal using wavelets functions. For each sample of an instrument it is automatically identified the attack, sustain and release regions. In each of the regions a decomposition process is carried out and finally it is got as a result the mean and variance of the wavelets coefficients. Those are the input data of the fuzzy or neural network used in the identification of the clarinet. The experiments show it is possible to acquire a low level of error rate.

Blind Separation of Speech Convolutive Mixtures via Time-Frequency Masking
abstract, pdf

An ideal binary masking, which specifies regions in the time-frequency domain whose concerned signal energy is greater than the interference signals is analyzed. The performance of the signal separation when these ideal binary masks are applied is evaluated. In the tests, these ideal masks remove almost all the interference from the other source of convolutive mixtures using simulated room impulses. A method for blind signal separation in the time-frequency domain using only the relative amplitude information of each time-frequency cluster cells is proposed . In reverberant environment the proposed method can not identify the clusters, but we may find out that the referring attenuation values of each source are concentrated in the extremities of the curve of relative attenuation histogram. Experimental results show that our proposed method can separate signals with little interference from the other source even in a real reverberant environment.