1,484 research outputs found
Sparse Gaussian Process Audio Source Separation Using Spectrum Priors in the Time-Domain
Gaussian process (GP) audio source separation is a time-domain approach that
circumvents the inherent phase approximation issue of spectrogram based
methods. Furthermore, through its kernel, GPs elegantly incorporate prior
knowledge about the sources into the separation model. Despite these compelling
advantages, the computational complexity of GP inference scales cubically with
the number of audio samples. As a result, source separation GP models have been
restricted to the analysis of short audio frames. We introduce an efficient
application of GPs to time-domain audio source separation, without compromising
performance. For this purpose, we used GP regression, together with spectral
mixture kernels, and variational sparse GPs. We compared our method with
LD-PSDTF (positive semi-definite tensor factorization), KL-NMF
(Kullback-Leibler non-negative matrix factorization), and IS-NMF (Itakura-Saito
NMF). Results show that the proposed method outperforms these techniques.Comment: Paper submitted to the 44th International Conference on Acoustics,
Speech, and Signal Processing, ICASSP 2019. To be held in Brighton, United
Kingdom, between May 12 and May 17, 201
Acoustically Inspired Probabilistic Time-domain Music Transcription and Source Separation.
PhD ThesisAutomatic music transcription (AMT) and source separation are important
computational tasks, which can help to understand, analyse and process music
recordings. The main purpose of AMT is to estimate, from an observed
audio recording, a latent symbolic representation of a piece of music (piano-roll).
In this sense, in AMT the duration and location of every note played is
reconstructed from a mixture recording. The related task of source separation
aims to estimate the latent functions or source signals that were mixed
together in an audio recording. This task requires not only the duration and
location of every event present in the mixture, but also the reconstruction
of the waveform of all the individual sounds. Most methods for AMT and
source separation rely on the magnitude of time-frequency representations
of the analysed recording, i.e., spectrograms, and often arbitrarily discard
phase information. On one hand, this decreases the time resolution in AMT.
On the other hand, discarding phase information corrupts the reconstruction
in source separation, because the phase of each source-spectrogram must
be approximated. There is thus a need for models that circumvent phase
approximation, while operating at sample-rate resolution.
This thesis intends to solve AMT and source separation together from
an unified perspective. For this purpose, Bayesian non-parametric signal
processing, covariance kernels designed for audio, and scalable variational
inference are integrated to form efficient and acoustically-inspired probabilistic
models. To circumvent phase approximation while keeping sample-rate
resolution, AMT and source separation are addressed from a Bayesian time-domain
viewpoint. That is, the posterior distribution over the waveform of
each sound event in the mixture is computed directly from the observed data.
For this purpose, Gaussian processes (GPs) are used to define priors over the
sources/pitches. GPs are probability distributions over functions, and its
kernel or covariance determines the properties of the functions sampled from
a GP. Finally, the GP priors and the available data (mixture recording) are
combined using Bayes' theorem in order to compute the posterior distributions
over the sources/pitches.
Although the proposed paradigm is elegant, it introduces two main challenges.
First, as mentioned before, the kernel of the GP priors determines the
properties of each source/pitch function, that is, its smoothness, stationariness,
and more importantly its spectrum. Consequently, the proposed model
requires the design of flexible kernels, able to learn the rich frequency content
and intricate properties of audio sources. To this end, spectral mixture
(SM) kernels are studied, and the Mat ern spectral mixture (MSM) kernel
is introduced, i.e. a modified version of the SM covariance function. The
MSM kernel introduces less strong smoothness, thus it is more suitable for
modelling physical processes. Second, the computational complexity of GP
inference scales cubically with the number of audio samples. Therefore, the
application of GP models to large audio signals becomes intractable. To
overcome this limitation, variational inference is used to make the proposed
model scalable and suitable for signals in the order of hundreds of thousands
of data points.
The integration of GP priors, kernels intended for audio, and variational
inference could enable AMT and source separation time-domain methods to
reconstruct sources and transcribe music in an efficient and informed manner.
In addition, AMT and source separation are current challenges, because
the spectra of the sources/pitches overlap with each other in intricate
ways. Thus, the development of probabilistic models capable of differentiating
sources/pitches in the time domain, despite the high similarity between
their spectra, opens the possibility to take a step towards solving source separation
and automatic music transcription. We demonstrate the utility of our
methods using real and synthesized music audio datasets for various types of
musical instruments
Control Digital para un sistema de video
Proyecto de Graduación (Licenciatura en Ingeniería Electrónica) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería Electrónica, 2003.Dentro de la problemática de desarrollo de sistemas para el transporte aéreo, estos deben cumplir con estrictas normas eléctricas y físicas para su aprobación y aprovechamiento. Debido a esta situación, los dispositivos de esta índole por lo general resultan muy costosos con respecto a los dispositivos que se utilizan en otras áreas que no sean la aviación. Esto obligó a crear un sistema que cumpla con todas las normas y regulaciones pertinentes, y a su vez que sea un sistema con una gran flexibilidad y amplias posibilidades de actualización y crecimiento.
Para el desarrollo de este proyecto, la empresa General Aerospace Inc., ubicada en la ciudad de Miami, Florida, y dedicada a la venta de servicios de ingeniería para la aviación, se adentró en el área de la manufactura de controles de sistemas de entretenimiento en aviones privados y comerciales.
Para cumplir con los requerimientos generales de energía y tamaño en aviones, se utilizó un sistema computacional mínimo basado en un microprocesador marca Hitachi de tipo RISC y tecnología CMOS de alta velocidad y baja potencia, que se convierte en el elemento central del sistema de control de dispositivos eléctricos en este medio de transporte. La información generada por el sistema se despliega a través de una pantalla de tipo LCD y el ingreso de datos por parte del usuario se realiza a través de una pantalla de tacto.
El sistema actuador que se implementó es un espacio de direcciones virtuales que permite la comunicación del sistema mínimo con múltiples controladores, tales como televisores, luces y otros a través de un puerto serie en formato RS-232.
Este sistema permite por tanto la adaptación de nuevos dispositivos de control, ya sea de audio, video o funciones electromecánicas a un bajo costo de implementación y desarrollo.GenAero Avionics Engineering Manufacturing
Intrinsic non-magnetic Josephson junctions in twisted bilayer graphene
Recent experiments have demonstrated the possibility to design highly
controllable junctions on magic angle twisted bilayer graphene, enabling the
test of its superconducting transport properties. We show that the presence of
chiral pairing in such devices manifests in the appearance of an anomalous
Josephson effect ( behavior) even in the case of symmetric junctions
and without requiring any magnetic materials or fields. Such behavior arises
from the combination of chiral pairing and nontrivial topology of the twisted
bilayer graphene band structure that can effectively break inversion symmetry.
Moreover, we show that the effect could be experimentally enhanced and
controlled by electrostatic tuning of the junction transmission properties
Contenido de Cadmio y Plomo en tejido de Hígado y Riñón en el Jote de Cabeza Colorada Cathartes aura (Linneo, 1758) de Chañaral, Desierto de Atacama, Chile
Indexación: Web of Science; ScieloThe Atacama region, Chile, presents one of the highest levels of mining exploitation of the country, which leads to high levels of contamination from mine tailings and other related environmental liabilities. One of the most complex situations occurred in the Chañaral city, north of Chile, where for over 50 years mine tailings were dumped on the coast, causing severe damage in the ecosystem. To evaluate the effects on terrestrial biota, we analyzed the concentration of cadmium and lead in tissues of Turkey Vulture (Cathartes aura). The results indicate that accumulation of cadmium in kidney was 10.31 μg/g (SD 8.00, range 0.27 to 20.73 μg/g) while in the liver was 5.24 μg/g (SD 8.00, range 0.49 to 19.70). There values are very high when compared to data for other birds with similar ecological role. In relation to the lead, concentration in liver was 0.86 μg/g (SD 2.03, range 0.15 - 7.90), while in kidney was 1.05 μg/g (DS 2.54, range 0.044 to 9.86), values considered within the normal range. It is interesting to analyze from the perspective of the availability of these metals in the mining tailings, where lead (1.57 to 21.2 μg/g) presented higher levels than cadmium (0.061 to 1.085 μg/g). The difference between organs may be related to the role of metallothionein. We discuss the role of Turkey Vulture as a bioindicator of environmental liabilities.La Región de Atacama, Chile, presenta uno de los mayores niveles de explotación minera del país, el cual a su vez genera altos niveles de contaminación por relaves mineros y otros pasivos ambientales relacionados. Una de las más complejas situaciones ocurrió en la ciudad de Chañaral, norte de Chile, donde fueron liberados relaves mineros a sus costas por sobre 50 años, causando graves daños en el ecosistema. Para evaluar los efectos en la biota terrestre, nosotros analizamos la concentración de Cadmio y Plomo en tejidos del Jote de Cabeza Colorada (Cathartes aura). Los resultados indican que la acumulación de Cadmio en el Riñón fue 10,31 μg/g (DS 8,00, rango 0,27 a 20,73 μg/g) mientras en el Hígado fue 5,24 μg/g (DS 8,00, rango 0,49 a 19,70). Estos valores son muy altos si se compara con datos de otras aves de similar rol ecológico. En relación al Plomo, la concentración en Hígado fue de 0,86 μg/g (DS 2,03, rango 0,15 a 7,90), mientras que en Riñón fue de 1,05 μg/g (DS 2,54, rango 0,044 a 9,86), valores considerados dentro del rango normal. Estos resultados son interesantes de analizar desde la perspectiva de la disponibilidad de estos metales en el relave minero, donde el Plomo (1,57 a 21,2 μg/g) presentó mayores niveles que el Cadmio (0,061 a 1,085 μg/g). La diferencia entre órganos puede ser relacionado al rol de las metalotioneinas. Discutimos el rol del Jote de Cabeza Colorada como bioindicador de contaminaciones ambientales.http://ref.scielo.org/86hcb
Implantación de plataforma Moodle para capacitaciones en empresa del sector químico
Para la empresa Químicos Pereira, la entrada de personal nuevo implica que alguien deberá capacitarlo y cuando se realiza este proceso de formación alguien debe dejar de lado sus tareas principales para poder llevarlas a cabo, esto afecta la productividad de esta persona que debe dejar de lado su puesto por períodos hasta de una semana para poder llevar a cabo las capacitaciones de personal nuevo.
Se busca con este proyecto establecer un procedimiento a través del cual se formalice el proceso de capacitaciones al interior de dicha empresa, mediante el uso de las llamadas herramientas TIC, asegurando que las capacitaciones se realicen de manera tal que minimicen la pérdida de tiempo que se dedica sólo a esta labor ya que no afectarán la productividad de ningún otro empleado, se brinden a todo el personal nuevo y estén disponibles cuando se requieran
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