Mejora de voz mediante redes neuronales profundas

En este Trabajo Fin de Grado se ha implementado un sistema de limpieza de ruido, en señales de voz, basado en redes neuronales profundas (DNNs). Con esto en mente se consiguió generar un sistema parametrizable y aplicable a diferentes objetivos, más allá del mencionado en este TFG. Como inspiración en el desarrollo y diseño de este proyecto se ha partido de un trabajo publicado en 2015 en IEEE Transactions on Audio, Speech, and Language Processing, titulado 'A Regression Approach to Speech Enhancement Based on Deep Neural Networks' y escrito por Chin-Hui Lee, Young Xu, Jun Du y Li-Rong Dai. Para la realización de este trabajo se ha requerido de la implementación de código en Python, más concretamente el uso de las librerías Theano y Blocks. Theano constituye una de las herramientas más extendidas en la implementación de sistemas de machine learning pero, dada su complejidad, se decidió compaginarla con la otra librería citada, Blocks. Esta actúa por encima de Theano y hace más sencilla la interpretación y manipulación de las herramientas. Se han usado dos bases de datos principales, para de señales de voz se ha utilizado TIMIT y para señales de ruido se ha utilizado HU; ambas tanto para entrenamiento como para pruebas, aunque se harán ciertos experimentos con otras bases de datos como son ALBAYZIN, para voz, y NOISEX, para ruido. Por otro lado, las bases de ruidos solo se usarán en el 'ensuciado' de los audios empleados para entrenar y para experimentos. Este 'ensuciado' se ha conseguido implementar mediante el uso de la herramienta FANT desarrollada en el proyecto AURORA, un software que permite la adición de señales de ruido a señales de voz con un Signal to Noise Ratio (SNR) controlable. Para la evaluación del sistema se ha utilizado el estándar de estimación objetiva de la calidad subjetiva PESQ de la ITU-T. El objetivo al usar esta herramienta es el de mejorar los resultados devueltos por ella para audios extraídos de la red neuronal con respecto a los audios ruidosos originales.This Bachelor Thesis has implemented a noise cleaning system, on voice signals, based on deep neural networks (DNNs). With this in mind, it has been achieved the generation of a parametrizable system that can be focused on different tasks, not only on the one that has been proved in this project. It has been taken, as inspiration for this project, the paper published in 2015 in IEEE Transactions on Audio, Speech, and Language Processing, titleled 'A Regression Approach to Speech Enhancement Based on Deep Neural Networks' and written by Chin-Hui Lee, Young Xu, Jun Du y Li-Rong Dai. Python has been used on the realization of this work; to be more precise, the libraries Thenao and Blocks. Thenao is one of the best and more used, around the world, tools in machine learning problems. Because of its complexity, it has been decided to use Blocks as well. This library works on a higher level than Theano and helps in the manipulation of the tools. There are two databases that have been used as main, TIMIT as voice database and HU as noise database, either train and test; however, other databases like ALBAYZIN, in voice, and NOISEX, in noise, have been used as well in test trials. Noise databases have been only used in the noise addition process for train and test. This process has been possible thanks to the FANT tool by AURORA, a software that allows users to add noise to a voice signal with a particular Signal to Noise Ratio (SNR). For the evaluation process, it has been used the standard of objective estimation of the subjective quality PESQ, by the ITU-T. The objective using this tool is to enhance the results thrown by it on the audio signals, extracted from the DNN, compared with the same result based on the original noisy voice signal

Spectral Properties and Stability in the Two-Dimensional Lattice-Hubbard Model

The two-dimensional Hubbard model on the square lattice is studied in the presence of lattice distortions in the adiabatic approximation. The self energy is computed within perturbation theory up to second order, which provides a way for studying the quasiparticle dispersion. We compute numerically the second order contribution to the self-energy using a standard fast Fourier transform algorithm for finite sizes system. The stability of the lattice distortions is investigated and a schematic phase diagram is drawn. The Fermi surface is analyzed for densities close to half filling, the presence of lattice distortions changes some spectral properties of the model and gives an anisotropic interacting Fermi surface. The spectral function is calculated along several lines in momentum space and the renormalized quasiparticle dispersion is obtained. The behavior of the density of states is shown for different values of the intrasite repulsion U in the different phases.Instituto de Física La Plat

Quantum phase diagram of a frustrated antiferromagnet on the bilayer honeycomb lattice

We study the spin-1/2 Heisenberg antiferromagnet on a bilayer honeycomb lattice including interlayer frustration. Using a set of complementary approaches, namely Schwinger bosons, dimer series expansion, bond operators, and exact diagonalization, we map out the quantum phase diagram. Analyzing ground state energies and elementary excitation spectra, we find four distinct phases, corresponding to three collinear magnetic long range ordered states, and one quantum disordered interlayer dimer phase. We detail, that the latter phase is adiabatically connected to an "exact" singlet product ground state of the the bilayer which exists along a line of maximum interlayer frustration. The order within the remaining three phases will be clarified.Comment: 12 pages, 12 figure

Spectral Properties and Stability in the Two-Dimensional Lattice-Hubbard Model

The two-dimensional Hubbard model on the square lattice is studied in the presence of lattice distortions in the adiabatic approximation. The self energy is computed within perturbation theory up to second order, which provides a way for studying the quasiparticle dispersion. We compute numerically the second order contribution to the self-energy using a standard fast Fourier transform algorithm for finite sizes system. The stability of the lattice distortions is investigated and a schematic phase diagram is drawn. The Fermi surface is analyzed for densities close to half filling, the presence of lattice distortions changes some spectral properties of the model and gives an anisotropic interacting Fermi surface. The spectral function is calculated along several lines in momentum space and the renormalized quasiparticle dispersion is obtained. The behavior of the density of states is shown for different values of the intrasite repulsion U in the different phases.Instituto de Física La Plat

Development and test of resistive superconducting fault current limiter; acting time and its recovery conditions

Resistive-type of superconducting fault current limiters (RSFCL) have been developed for medium voltage class aiming to operate at 1 MVA power capacity and short time recovery (< 2 s). A RSFCL in form of superconducting modular device was designed and constructed using 50 m-length of YBCO coated conductor tapes for operation under 1 kV / 1 kA and acting time of 0.1 s. In order to increase the acting time the RSFCL was combined with an air-core reactor in parallel to increase the fault limiting time up to 1 s. The tests determined the electrical and thermal characteristics of the combined resistive/ inductive protection unit. The combined fault current limiter reached a limiting current of 583 A, corresponding to a limiting factor of 3.3 times within an acting time of up to 1 s

Use of Industrial Waste for the Optimization of Ceramic Construction Materials

The massive growth of the ceramic industry and the consequent demand for construction materials worldwide has motivated the search for alternative solutions aimed at reducing the use of mineral / natural resources as the main source of raw materials. One of the strategies frequently adopted by the scientific community is the reuse of industrial waste. It is beneficial not only to reduce the overexploitation of mineral resources but also to reduce the environmental, economic and social impacts resulting from their incorrect disposal/treatment and consequent deposition on land unsuitable or that purpose. Duetoconsiderationssuchasphysico-mechanical characteristics and the high production rate, two different types of industrial waste were selected for this work, ashes resulting from the burning of coal in thermoelectric power plant, commonly known as bottom ash (B), and the Marble Powder (MP). It was intended to test the technological feasibility of the manufacture of ceramic materials produced from clay mixtures containing these two residues. For this purpose, the fine fraction(&lt;63μm)obtained from the sieving of the marbleresidue(MR)and slag(Bf)was used,aswellasacoarsergrainslagfractionrangingfrom63-125μm(Bg). The resulting test samples were subjected to a firing of 950 °C under an oxidizing atmosphere, following a primary drying process. Faced with the standard values, the new ceramic materials obtained from MP have seen their mechanical and porous characteristics decrease and increase, respectively. Atthesametime,althoughtheadditionofBinno way influenced the mechanical characteristics,a significant improvement the porous characteristic was observed. The incorporation of these residues produced a color very close to the original sample material. Keywords: industrial waste, ceramic, construction materials, bottom ash, Marble Powde

Combined analytical and numerical approach to study magnetization plateaux in doped quasi-one-dimensional antiferromagnets

We investigate the magnetic properties of quasi-one-dimensional quantum spin-S antiferromagnets. We use a combination of analytical and numerical techniques to study the presence of plateaux in the magnetization curve. The analytical technique consists in a path integral formulation in terms of coherent states. This technique can be extended to the presence of doping and has the advantage of a much better control for large spins than the usual bosonization technique. We discuss the appearance of doping-dependent plateaux in the magnetization curves for spin-S chains and ladders. The analytical results are complemented by a density matrix renormalization group (DMRG) study for a trimerized spin-1/2 and anisotropic spin-3/2 doped chains.Instituto de Física La Plat

Current jumps in flat-band ladders with Dzyaloshinskii-Moriya interactions

Localized magnons states, due to flat bands in the spectrum, is an intensely studied phenomenon and can be found in many frustrated magnets of different spatial dimensionality. The presence of Dzyaloshinskii-Moriya (DM) interactions may change radically the behavior in such systems. In this context, we study a paradigmatic example of a one-dimensional frustrated antiferromagnet, the sawtooth chain in the presence of DM interactions. Using both path integrals methods and numerical Density Matrix Renormalization Group, we revisit the physics of localized magnons and determine the consequences of the DM interaction on the ground state. We have studied the spin current behavior, finding three different regimes. First, a Luttinger-liquid regime where the spin current shows a step behavior as a function of parameter D, at a low magnetic field. Increasing the magnetic field, the system is in the Meissner phase at the m = 1/2 plateau, where the spin current is proportional to the DM parameter. Finally, further increasing the magnetic field and for finite D there is a small stiffness regime where the spin current shows, at fixed magnetization, a jump to large values at D = 0, a phenomenon also due to the flat band.Fil: Acevedo, Santiago Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Pujol, P.. Université Paul Sabatier; Francia. Université de Toulouse; FranciaFil: Lamas, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentin