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

Vortex Noise from Rotating Cylindrical Rods

A series of round rods of the some diameter were rotated individually about the mid-point of each rod. Vortices are shed from the rods when in motion, giving rise to the emission of sound. With the rotating system placed in the open air, the distribution of sound in space, the acoustical power output, and the spectral distribution have been studied. The frequency of emission of vortices from any point on the rod is given by the formula von Karman. From the spectrum estimates are made of the distribution of acoustical power along the rod, the amount of air concerned in sound production, the "equivalent size" of the vortices, and the acoustical energy content for each vortex

Evaluation of live human-computer music-making: Quantitative and qualitative approaches

NOTICE: this is the author’s version of a work that was accepted for publication in International Journal of Human-Computer Studies. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in International Journal of Human-Computer Studies, [VOL 67,ISS 11(2009)] DOI: 10.1016/j.ijhcs.2009.05.00

Short term, low strain radial tensile stiffness of a triaxial geogrid with integral junctions

This work starts by introducing the triaxial geogrid to be tested, TriAx®, along with its intended use and applications. It identifies that stabilisation and interlock is well understood but the radial, low-strain, tensile load-strain stiffness of these geogrids is not. A detailed review of the development of geogrids with integral junctions is then undertaken, highlighting how geogrids were first produced in the 1950’s and how they have been developed up to the point of starting this work. Index and performance testing of geogrids with integral junctions are described. The specific geogrid for testing, TriAx® TX160, is introduced along with the methods of testing and the test programmes defined. Q.C., Index, and uniaxial creep testing is defined, carried out, and the data analysed and compared. A secondary crystallisation mechanism is established and occurs over time after production. Quadrant radial creep testing of TriAx® TX160 geogrid is introduced. To date wide-width, uniaxial constant rate of strain (CRS) tensile tests carried out in multiple directions have been used to determine the radial stiffness property, but the validity of this approach has not been investigated. Therefore, a new, in-plane, radial tensile test apparatus and test methodology has been developed for this purpose. The apparatus and sample geometry are defined, and the test data and analysis presented. All low strain behaviour from the three different test methodologies, constant rate of strain, uniaxial creep, and radial creep, were combined and compared with a possible “locked-in stress” being identified. The data from all three test methodologies are replotted with the possible locked-in stress. Upon comparing data obtained from this new radial tensile test and multi-directional uniaxial tensile testing, the data was found to be closely correlated. Thus, the multi-directional, uniaxial CRS tensile test is shown to be a reasonable and conservative means of determining the short-term, low-strain, radial tensile stiffness of multi-axial geogrids and the need for more elaborate testing methodologies is not required

PEArL: A Systems Approach to Demonstrating Authenticity in Information Systems Design

The process of information systems (IS) design has been dominated by the demands inherent in providing a technical solution to a perceived problem or need. Engineering IS design methods applied in order to satisfy the problem situation tend to have a preoccupation with verifying specifications as being mathematically correct. Difficulties arise when the ideas underpinning verification are extended in an attempt to ‘prove’ the validity of a proposed design for an IS. A pure engineering approach does not facilitate a response to the subjective elements within social situations, which experience has shown to be essential in demonstrating the pertinence of new designs to those concerned. We suggest that, by applying interpretivist systems ideas, it is possible to support concerned individuals in reflecting upon crucial aspects of the inquiry, enabling those individuals to judge the relevance or ‘authenticity’ of the learning, according to their own values and beliefs. The elements of participants, engagement, authority, relationships and learning are suggested as being crucial. These make up the mnemonic PEArL, which is offered as an aide-mémoire for those concerned with IS design

Delayed Decision-making in Real-time Beatbox Percussion Classification

This is an electronic version of an article published in Journal of New Music Research, 39(3), 203-213, 2010. doi:10.1080/09298215.2010.512979. Journal of New Music Research is available online at: www.tandfonline.com/openurl?genre=article&issn=1744-5027&volume=39&issue=3&spage=20

Poisson's Ratios and Volume Changes for Plastically Orthotropic Material

Measurements of Poisson's ratios have been made in three orthogonal directions on aluminum alloy blocks in compression and on stainless-steel sheet in both tension and compression. These measurements, as well as those obtained by density determinations, show that there is no permanent plastic change in volume within the accuracy of observation. A method is suggested whereby a correlation may be effected between the measured individual values of the Poisson's ratios and the stress-strain curves for the material. Allowance must be made for the difference in the stress-strain in tension and compression; this difference, wherever it appears, is accompanied by significant changes in the Poisson's ratios