Deep Learning for Audio Effects Modeling

PhD Thesis.Audio effects modeling is the process of emulating an audio effect unit and seeks to recreate the sound, behaviour and main perceptual features of an analog reference device. Audio effect units are analog or digital signal processing systems that transform certain characteristics of the sound source. These transformations can be linear or nonlinear, time-invariant or time-varying and with short-term and long-term memory. Most typical audio effect transformations are based on dynamics, such as compression; tone such as distortion; frequency such as equalization; and time such as artificial reverberation or modulation based audio effects. The digital simulation of these audio processors is normally done by designing mathematical models of these systems. This is often difficult because it seeks to accurately model all components within the effect unit, which usually contains mechanical elements together with nonlinear and time-varying analog electronics. Most existing methods for audio effects modeling are either simplified or optimized to a very specific circuit or type of audio effect and cannot be efficiently translated to other types of audio effects. This thesis aims to explore deep learning architectures for music signal processing in the context of audio effects modeling. We investigate deep neural networks as black-box modeling strategies to solve this task, i.e. by using only input-output measurements. We propose different DSP-informed deep learning models to emulate each type of audio effect transformations. Through objective perceptual-based metrics and subjective listening tests we explore the performance of these models when modeling various analog audio effects. Also, we analyze how the given tasks are accomplished and what the models are actually learning. We show virtual analog models of nonlinear effects, such as a tube preamplifier; nonlinear effects with memory, such as a transistor-based limiter; and electromechanical nonlinear time-varying effects, such as a Leslie speaker cabinet and plate and spring reverberators. We report that the proposed deep learning architectures represent an improvement of the state-of-the-art in black-box modeling of audio effects and the respective directions of future work are given

Transitividad del verbo ser

In analysing sentences in which the Spanish neuter pronoun lo, followed by ser [to be], was used to reproduce the meaning of transitive verbs (as in “No se pudieron desembarcar las mercaderías, pero lo fue la gente”), Andres Bello, Grand Master of Grammar, remarked in paragraph 301 of his Grammar: “The pronoun lo, which represents predicates, is the accusative case of ello”. And as he writes accusative he undoubtedly speaks of a transitive verb; so in Note VIII (“Lo” predicado) we read: “Is verb ser [to be] associated with the accusative case? Why not? Why should we shut our eyes to an obvious, indisputable fact?It’s a received principle that for a verb the fact of being active or neuter (stative) does not  depend on its meaning, inasmuch as an active verb of a tongue may correspond to a neuter verb of another tongue.” We shall build upon this idea.Andrés Bello, el Gran Maestro de la gramática, analizando oraciones en que el pronombre lo seguido de ser reproduce el significado de verbos transitivos (como en “No se pudieron desembarcar las mercaderías, pero lo fue la gente”), comentó en el § 301 de su Gramática: “Este lo representativo de predicados es el caso complementario acusativo de ello”. Y cuando escribe acusativo ya nos está hablando de verbo transitivo; así en la Nota VIII (“Lo” predicado) retoma el tema y dice: “¿El verbo ser con acusativo? ¿Y por qué no? ¿Por qué cerrar los ojos a un hecho manifiesto en que no cabe disputa? Es un principio recibido que el ser activo o neutro un verbo no depende de su significación, puesto que a un verbo neutro en una lengua corresponde muchas veces un verbo activo en otra.”Desarrollaremos esta idea

Genetic diversity of terricolous Peltigera cyanolichen communities in different conservation states of native forest from southern Chile

Decreasing quality of forest habitats is among the major factors leading to a loss of epiphytic lichen diversity. However, there is little information about how this factor influences the diversity of terricolous lichens, which do not grow over living trees and could be less susceptible to such disturbances. In this work we describe the genetic diversity of Peltigera terricolous cyanolichens and their cyanobiont (Nostoc) from three habitats at the Karukinka Natural Park (Tierra del Fuego, southern Chile), which represent different conservation states: native mature-forest (low disturbance intensity), native youngforest (medium disturbance intensity) and grassland (high disturbance intensity). In both forest contexts, a higher diversity and a higher number of unique OTUs (operational taxonomic units) were found. In contrast, in the grassland, the diversity was lower and the Peltigera species were mostly cosmopolitan. The presence of unique OTUs and the higher diversity of lichens in native forest areas highlight the importance of their preservation, indicating that decreasing forest quality also has a negative impact on terricolous lichens diversity. [Int Microbiol 2013; 16(4):243-252]Keywords: Peltigera · Nostoc · lichens · genetic diversity · Karukinka Natural Park · southern Chil

Fetoplacental Vascular Endothelial Dysfunction as an Early Phenomenon in the Programming of Human Adult Diseases in Subjects Born from Gestational Diabetes Mellitus or Obesity in Pregnancy

Gestational diabetes mellitus (GDM) and obesity in pregnancy (OP) are pathological conditions associated with placenta vascular dysfunction coursing with metabolic changes at the fetoplacental microvascular and macrovascular endothelium. These alterations are seen as abnormal expression and activity of the cationic amino acid transporters and endothelial nitric oxide synthase isoform, that is, the “endothelial L-arginine/nitric oxide signalling pathway.” Several studies suggest that the endogenous nucleoside adenosine along with insulin, and potentially arginases, are factors involved in GDM-, but much less information regards their role in OP-associated placental vascular alterations. There is convincing evidence that GDM and OP prone placental endothelium to an “altered metabolic state” leading to fetal programming evidenced at birth, a phenomenon associated with future development of chronic diseases. In this paper it is suggested that this pathological state could be considered as a metabolic marker that could predict occurrence of diseases in adulthood, such as cardiovascular disease, obesity, diabetes mellitus (including gestational diabetes), and metabolic syndrome

Design of experiments applied to lithium-ion batteries : a literature review

The statistical design of experiments methodology (DoE) has been a valuable tool since its conception for the understanding of the relationship between factors and responses. Although it has been employed successfully in different research fields and industries for years, its application to the evaluation of lithium-ion batteries (LIBs) is just getting recognition. LIBs are one of the most promising technologies for a complete transition to sustainable energies, are the main technology behind electric vehicles and are fundamental for the continual development of portable electronic devices. This paper presents a critical literature review of the available DoE works applied to the manufacturing and characterisation of LIBs. An overview of DoE and the most important available designs are first presented, followed by a general introduction of the statistical analysis required for the interpretation of the results including regression models. Several aspects of the LIBs such as ageing, capacity, electrode formulation, active material synthesis, thermal design, charging and parameterisation are discussed based on the main objective of the respective DoE studies found in the literature. A case study is presented to visualise the practical application of DoE to the LIBs field. Perspectives and future outlook are given to highlight opportunities and potential areas of research in the application of traditional and modern designs to the LIB’s field. This critical review contributes to a better understanding of the DoE methodology with a focus on LIBs or LIBs related aspects which will lead to faster developments in the field

Direct instruction wakeup for out-of-order processors

Instruction queues consume a significant amount of power in high-performance processors, primarily due to instruction wakeup logic access to the queue structures. The wakeup logic delay is also a critical timing parameter. This paper proposes a new queue organization using a small number of successor pointers plus a small number of dynamically allocated full successor bit vectors for cases with a larger number of successors. The details of the new organization are described and it is shown to achieve the performance of CAM-based or full dependency matrix organizations using just one pointer per instruction plus eight full bit vectors. Only two full bit vectors are needed when two successor pointers are stored per instruction. Finally, a design and pre-layout of all critical structures in 70 nm technology was performed for the proposed organization as well as for a CAM-based baseline. The new design is shown to use 1/2 to 1/5th of the baseline instruction queue power, depending on queue size. It is also shown to use significantly less power than the full dependency matrix based design.Peer ReviewedPostprint (published version

Massive open star clusters using the VVV survey III: A young massive cluster at the far edge of the Galactic bar

Context: Young massive clusters are key to map the Milky Way's structure, and near-IR large area sky surveys have contributed strongly to the discovery of new obscured massive stellar clusters. Aims: We present the third article in a series of papers focused on young and massive clusters discovered in the VVV survey. This article is dedicated to the physical characterization of VVV CL086, using part of its OB-stellar population. Methods: We physically characterized the cluster using $JHK_S$ near-infrared photometry from ESO public survey VVV images, using the VVV-SkZ pipeline, and near-infrared $K$-band spectroscopy, following the methodology presented in the first article of the series. Results: Individual distances for two observed stars indicate that the cluster is located at the far edge of the Galactic bar. These stars, which are probable cluster members from the statistically field-star decontaminated CMD, have spectral types between O9 and B0V. According to our analysis, this young cluster ($1.0$ Myr $<$ age $< 5.0$ Myr) is located at a distance of $11^{+5}_{-6}$ kpc, and we estimate a lower limit for the cluster total mass of $(2.8^{+1.6}_{-1.4})\cdot10^3 {M}_{\odot}$. It is likely that the cluster contains even earlier and more massive stars.Comment: Accepted for publication as a Letter in A&