Edifying spectacle at UCD

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Boylan's Fugue in 'Sirens'

Recent discoveries in genetic studies require a revision of the fugal structure in ‘Sirens.’ We hope we can shed light on some of the remaining unsolved questions by applying these studies to an interdisciplinary approach. We will put forward our point of view on the most controversial debate on music in Joyce: does this episode of Ulysses contain the eight parts of a fuga per canonem, as the author asserted, and how can we find these parts. Our study is based on the The Sirens Copybook manuscript authenticated by Michael Groden, as well as on the further analysis by two scholars, Daniel Ferrer and Susan Brown. We believe that the role of the character Blazes Boylan in ‘Sirens’ is crucial to divide the episode in eight parts chronologically. First of all, we must point out that some of the concepts that are being used for this interdisciplinary analysis are not unambiguous and depend on the field of study alluded to. A good example is the notion of “theme,” which appears in literature as the main subject of a text, but in music it is understood as a synonym for motif, the musical material that provides a work with its own identity. Some problems of interpretation arise when this term is applied in both music and literature without a clear distinction, such as in the discussion of the eight fugal parts in ‘Sirens.’ Two authors – Stuart Gilbert and Susan Brown – claim to identify these eight sections by mentioning the “themes.” Also, the accuracy of an interdisciplinary study depends on the meticulous use of homogenous sources for the musical concepts. If not, one may argue that the scholar quotes one dictionary or another depending on his/her own interests. Susan Brown recently established that Joyce’s musical knowledge was based on the Grove’s Dictionary of Music (in this paper we will be using the abbreviation GDM). Despite detractors of Brown’s thesis, like Michelle Witen, we believe that for all practical purposes this encyclopaedia is the most useful source for establishing a standardised musical terminology. Every definition of a musical term for this research has been taken from this source

A compact formula for the derivative of a 3-D rotation in exponential coordinates

We present a compact formula for the derivative of a 3-D rotation matrix with respect to its exponential coordinates. A geometric interpretation of the resulting expression is provided, as well as its agreement with other less-compact but better-known formulas. To the best of our knowledge, this simpler formula does not appear anywhere in the literature. We hope by providing this more compact expression to alleviate the common pressure to reluctantly resort to alternative representations in various computational applications simply as a means to avoid the complexity of differential analysis in exponential coordinates.Comment: 6 page

Focus Is All You Need: Loss Functions For Event-based Vision

Event cameras are novel vision sensors that output pixel-level brightness changes ("events") instead of traditional video frames. These asynchronous sensors offer several advantages over traditional cameras, such as, high temporal resolution, very high dynamic range, and no motion blur. To unlock the potential of such sensors, motion compensation methods have been recently proposed. We present a collection and taxonomy of twenty two objective functions to analyze event alignment in motion compensation approaches (Fig. 1). We call them Focus Loss Functions since they have strong connections with functions used in traditional shape-from-focus applications. The proposed loss functions allow bringing mature computer vision tools to the realm of event cameras. We compare the accuracy and runtime performance of all loss functions on a publicly available dataset, and conclude that the variance, the gradient and the Laplacian magnitudes are among the best loss functions. The applicability of the loss functions is shown on multiple tasks: rotational motion, depth and optical flow estimation. The proposed focus loss functions allow to unlock the outstanding properties of event cameras.Comment: 29 pages, 19 figures, 4 table

Experimental study of the main component of a technology for its use in space propulsion at cryogenic conditions

As the aerospace technology progresses, new challenges emerge which have to be managed and solved to make future space exploration missions possible. This study faces one of these challenges: The efficient long-term storage of cryogenic propellant. Nowadays the available technology is not sufficiently evolved to ensure thermal isolation throughout the entire mission which can be months or even years. It's a given fact that propellant lost due to boil-off will happen. This inevitably calls for the imperative necessity of controlling the bubbles generated by the boiling for two reasons: Firstly, to avoid the loss of thousands of litres of propellant and secondly to prevent the possible generation of foam structures, which could be hazardous at different stages of the mission. Ones of the technology proposed by the UPC Microgravity laboratory to control and eliminate the bubbles is based on the use of ultrasonic acoustic waves, created by piezoelectric devices. The objective of this study is to find a piezoelectric material that works correctly at cryogenic temperatures, more exactly at -253ºC which is the boiling temperature of liquid hydrogen, to obtain the control of the bubbles in the liquid. Our initial hypothesis is based on the possibility of controlling the bubble formation and dynamics in boiling in cryogenic propellant storage tanks by means of an acoustic wave generated by a piezoelectric device. At present, there isn't any piezoelectric ceramic material that works efficiently and is durable at such low temperatures. In fact, the piezoelectric effect has barely been studied at these temperatures, probably due to the lack of applications. However, there are studies about bubble control in liquids by means of acoustic waves in microgravity. The research for a good piezoelectric material for this purpose turns out to be a challenge without any guaranteed success. On the other hand, if such a material was found, it could be used in future space missions. This study is part of an investigation project subsidized by the government for its originality and innovation in the aerospace sector, due to it's the first to focus this problem to the real conditions at cryogenic conditions. Its main focus is on the cryogenic conditions of fluids. To carry out the study, piezoelectric ceramics have been procured and selected specifically for their promising properties, to carry out the intended experiments. The measurements were obtained in the Piezoelectric Materials laboratory of Physics Department of the UPC. The results show that the intended application is not feasible, since the piezoelectric properties of all ceramic materials studied have been decreasing exponentially with temperature up to a minimum at which the desired performance in the targeted range of operating temperatures doesn't appear at all. We conclude that the use of these ceramics, which by its design were initially very promising, must be discarded for the insufficient piezoelectric response under cryogenic conditions. However, the aim of the project is not completely discarded, since there are other possible materials, like piezoelectric crystals that could work as required at very low temperatures

Introducción a la difusión en el tratamiento de imágenes

La idea que motiva el estudio de la difusión anisótropa en el tratamiento de imágenes es la búsqueda de métodos de suavizamiento de imágenes (“filtros”) que atenúen el ruido a la vez que respeten la información de bordes (“señal”) de la imagen