Visual analysis for drum sequence transcription

A system is presented for analysing drum performance video sequences. A novel ellipse detection algorithm is introduced that automatically locates drum tops. This algorithm fits ellipses to edge clusters, and ranks them according to various fitness criteria. A background/foreground segmentation method is then used to extract the silhouette of the drummer and drum sticks. Coupled with a motion intensity feature, this allows for the detection of ‘hits’ in each of the extracted regions. In order to obtain a transcription of the performance, each of these regions is automatically labeled with the corresponding instrument class. A partial audio transcription and color cues are used to measure the compatibility between a region and its label, the Kuhn-Munkres algorithm is then employed to find the optimal labeling. Experimental results demonstrate the ability of visual analysis to enhance the performance of an audio drum transcription system

Recovery and reuse of discontinuous carbon fibres by solvolysis: Realignment and properties of remanufactured materials

Discontinuous carbon fibre tows were recovered after solvolysis of an aeronautic type composite made with RTM6 epoxy resin. A Sohxlet extraction method was used to quantify the organic residue on the fibre tows and showed that less than 3 wt% was remaining on the surface. The recovered tows were therefore reused directly to manufacture a plate with randomly distributed carbon fibres and then three plates with realigned carbon fibres. The latter were then characterised and tested and the results obtained were compared to the material manufactured using the same type of virgin fibres by the same method. The materials made from recycled carbon fibres showed very good properties in comparison to the virgin fibre material, despite the presence of flaws such as quality of the fibre surface after solvolysis, alignment and voids). This is the first time in the open literature that carbon fibres recovered from solvolysis were reused in this way together with characterisation of the resulting materials

Performances of composites made from different recycled carbon fibre semi-products

Recycled carbon fibres (rCF) were generally chosen for their low price and environmental features. However, performances of composites made of recycled carbon fibres are often too low to compete with lightweight alloys and glass fibre composites materials. As performances of rCF composites depend strongly on the fibres architecture, new semi-products with long and aligned recycled carbon fibres were developed by MANIFICA (Cleansky European Project). The use of long (up to 250mm) and highly aligned recycled fibres now provides rCF composites with excellent mechanical properties. The purpose of this work is to assess the performances of composites manufactured with these new rCF semi-products. Semi-products with distinct architectures developed by MANIFICA are first presented. Then mechanical performances of composite plates manufactured from the different semi-products are evaluated. Results are finally compared in order to identify the effect of the manufacturing parameters of the semi-products on the final composite properties. This crucial information will allow end-users to select the right semi-product to design recycled carbon fibre composite innovative parts

Integrality of the Chern character in small codimension

We prove an integrality property of the Chern character with values in Chow groups. As a consequence we obtain, for a prime number p, a construction of the p-1 first homological Steenrod operations on Chow groups modulo p and p-primary torsion, over an arbitrary field. We provide applications to the study of correspondences between algebraic varieties.Comment: Correct some typos; add an appendix extending the results to schemes of finite type over a regular bas

Simplification of requalification procedure of outdated carbon/epoxy prepregs and scenarios of reuse

As a result of their combined high mechanical performances and easy processability, carbon/epoxy prepregs are widely used in the manufacture of aerostructures. The resin of these materials is in an intermediate state of polymerisation which makes these materials perishable. Drastic manufacture conditions lead continuously to the generation of expired prepregs that, today, can no more be used in the aeronautic industry nor in other industries. Although requalification procedure can be carried out, its high cost does not always justify such a procedure. This is why large quantities of expired prepregs are send to landfill. The objective of the Cleansky project MANIFICA is to set up a complete recycling chain of carbon fibre composites “from aeronautic waste to innovative composite parts”. The aim of this work is to propose a simplified requalification procedure by avoiding unnecessary tests. These studies are illustrated by property measures on compliant and expired prepregs. The main results were that in most cases, aging induces processing difficulties while mechanical performance remains unaffected. It was also shown that a simpler requalification procedure was possible and that expired prepregs can be reused without loss of performance outside the aeronautical field. Rather than considering expired material as waste, MANIFICA offers several new reuse scenario

Performance and applicability of a 2.5-D ice-flow model in the vicinity of a dome

This project is supported by the Université Grenoble Alpes in the framework of the proposal called Grenoble Innovation Recherche AGIR.Three-dimensional ice flow modelling requires a large number of computing resources and observation data, such that 2-D simulations are often preferable. However, when there is significant lateral divergence, this must be accounted for (2.5-D models), and a flow tube is considered (volume between two horizontal flowlines). In the absence of velocity observations, this flow tube can be derived assuming that the flowlines follow the steepest slope of the surface, under a few flow assumptions. This method typically consists of scanning a digital elevation model (DEM) with a moving window and computing the curvature at the centre of this window. The ability of the 2.5-D models to account properly for a 3-D state of strain and stress has not clearly been established, nor their sensitivity to the size of the scanning window and to the geometry of the ice surface, for example in the cases of sharp ridges. Here, we study the applicability of a 2.5-D ice flow model around a dome, typical of the East Antarctic plateau conditions. A twin experiment is carried out, comparing 3-D and 2.5-D computed velocities, on three dome geometries, for several scanning windows and thermal conditions. The chosen scanning window used to evaluate the ice surface curvature should be comparable to the typical radius of this curvature. For isothermal ice, the error made by the 2.5-D model is in the range 0-10ĝ % for weakly diverging flows, but is 2 or 3 times higher for highly diverging flows and could lead to a non-physical ice surface at the dome. For non-isothermal ice, assuming a linear temperature profile, the presence of a sharp ridge makes the 2.5-D velocity field unrealistic. In such cases, the basal ice is warmer and more easily laterally strained than the upper one, the walls of the flow tube are not vertical, and the assumptions of the 2.5-D model are no longer valid.Publisher PDFPeer reviewe

Interaction microstructure/propriétés dans un matériau composite à fibres de carbone recyclées

Il existe aujourd’hui plusieurs techniques efficaces de séparation fibres / matrice pour recycler les fibres de carbone issues de matériaux composites. Les projets de développement de ces techniques thermiques, fluides supercritiques ou chimiques ont donné d’excellents résultats (RECCOMP, HIRECAR, Aerdeco, RECCO), voire [1], [2]. Les techniques les plus efficaces permettent d’obtenir des fibres de carbone de 2° génération avec une très faible perte de propriété (inférieure à 5%) [3], [4]. Le réalignement des fibres recyclées s’avère un point clé dans l’obtention de nouveaux matériaux composites utilisables pour des applications structurelles à forte valeur ajoutée. A ce titre, nous présenterons dans une première partie, un procédé innovant de remise en forme inventé à l’I2M de Bordeaux qui génère des semi-produits de fibres de carbone de 2° génération à partir de morceaux de tissus de carbone post-solvolyse. Dans une seconde partie, nous étudions l’impact de la nature des fibres, du taux de réalignement et de la dispersion de la densité sur la résistance des matériaux composites de 2° génération (contenant des fibres recyclées remises en forme). La maîtrise des relations paramètres de remise en forme qualité du semi-produit résistance du matériau recyclé permettra alors d’envisager des applications structurales pour de la fibre de carbone recyclée. La conclusion de cette présentation est qu’il est impératif d’étudier les facettes chimiques (séparation fibre/matrice) et mécaniques (remise en forme des fibres solvolysées) du recyclage pour concevoir des semi-produits de fibres recyclées et ouvrir les voies d’une utilisation de haute qualité des fibres recyclées. Références : [1] Soraia Pimenta, Silvestre T. Pinho “Recycling carbon fibre reinforced polymers for structural applications: Technology review and market outlook” Waste Management 31 (2011) 378–392 [2] Carbon recycling: a soluble problem » REINFORCED plastics MAY 2009 [3] S.J. Pickering “Recycling technologies for thermoset composite materials—current status” Composites: Part A 37 (2006) 1206–1215 [4] Yongxiang Yang, Rob Boom, Brijan Irion, Derk-Jan van Heerden, Pieter Kuiper, Hans de Wit “Recycling of composite materials” Chemical Engineering and Processing 51 (2012) 53– 6

Automatic Labelling of Tabla Signals

Most of the recent developments in the field of music indexing and music information retrieval are focused on western music. In this paper, we present an automatic music transcription system dedicated to Tabla - a North Indian percussion instrument. Our approach is based on three main steps: firstly, the audio signal is segmented in adjacent segments where each segment represents a single stroke. Secondly, rhythmic information such as relative durations are calculated using beat detection techniques. Finally, the transcription (recognition of the strokes) is performed by means of a statistical model based on Hidden Markov Model (HMM). The structure of this model is designed in order to represent the time dependencies between successives strokes and to take into account the specificities of the tabla score notation (transcription symbols may be context dependent). Realtime transcription of Tabla soli (or performances) with an error rate of 6.5% is made possible with this transcriber. The transcription system, along with some additional features such as sound synthesis or phrase correction, are integrated in a user-friendly environment called Tablascope

Simulations of the Greenland ice sheet 100 years into the future with the full Stokes model Elmer/Ice

第2回極域科学シンポジウム/第34回気水圏シンポジウム 11月15日（火） 統計数理研究所 セミナー室