Augmented base loci and restricted volumes on normal varieties

We extend to normal projective varieties defined over an arbitrary algebraically closed field a result of Ein, Lazarsfeld, Musta\c{t}\u{a}, Nakamaye and Popa characterizing the augmented base locus (aka non-ample locus) of a line bundle on a smooth projective complex variety as the union of subvarieties on which the restricted volume vanishes. We also give a proof of the folklore fact that the complement of the augmented base locus is the largest open subset on which the Kodaira map defined by large and divisible multiples of the line bundle is an isomorphism.Comment: 7 pages. v2: we made a small modification of the statement of Lemma 2.4, a few minor corrections and updated reference

A space-averaged model of branched structures

Many biological systems and artificial structures are ramified, and present a high geometric complexity. In this work, we propose a space-averaged model of branched systems for conservation laws. From a one-dimensional description of the system, we show that the space-averaged problem is also one-dimensional, represented by characteristic curves, defined as streamlines of the space-averaged branch directions. The geometric complexity is then captured firstly by the characteristic curves, and secondly by an additional forcing term in the equations. This model is then applied to mass balance in a pipe network and momentum balance in a tree under wind loading.Comment: 10 pages, 11 figure

Drag Reduction, from Bending to Pruning

Most plants and benthic organisms have evolved efficient reconfiguration mechanisms to resist flow-induced loads. These mechanisms can be divided into bending, in which plants reduce their sail area through elastic deformation, and pruning, in which the loads are decreased through partial breakage of the structure. In this work, we show by using idealized models that these two mechanisms or, in fact, any combination of the two, are equally efficient to reduce the drag experienced by terrestrial and aquatic vegetation.Comment: 5 pages, 5 figure

Effect of the scatter between CPTU measured parameters in soil classification

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Simulation en laboratoire de la filtration des moraines non plastiques

Suffosion et critère de stabilité -- Critères de filtres -- Travaux antérieurs par Loungnarath (1996) et Dulau (1997) -- Essais au petit filtramètre -- Essais au filtramètre horizontal -- Procédures suivies lors d'un essai -- Petit filtramètre -- Filtramètre horizontal

Plane Wave Imaging for ultrasonic non-destructive testing: Generalization to multimodal imaging

Pre-printInternational audienceThis paper describes a new ultrasonic array imaging method for Non-Destructive Testing (NDT) which is derived from the medical Plane Wave Imaging (PWI) technique. The objective is to perform fast ultrasound imaging with high image quality. The approach is to transmit plane waves at several angles and to record the back-scattered signals with all the array elements. Focusing in receive is then achieved by coherent summations of the signals in every point of a region of interest. The medical PWI is generalized to immersion setups where water acts as a coupling medium and to multimodal (direct, half-skip modes) imaging in order to detect different types of defects (inclusions, porosities, cracks). This method is compared to the Total Focusing Method (TFM) which is the reference imaging technique in NDT. First, the two post-processing algorithms are described. Then experimental results with the array probe either in contact or in immersion are presented. A good agreement between the TFM and the PWI is observed, with three to ten times less transmissions required for the PWI

Multimodal Plane Wave Imaging for Non-destructive Testing

International audienceUltrasonic imaging with high frame rates is of great interest in Non-Destructive Testing (NDT) to perform fast inspections. In this communication, we propose a new fast imaging method for NDT which is derived from the medical Plane Wave Imaging (PWI). The PWI method is applied to immersion-testing configurations (plane or complex water/steel interface between the probe and the image area) and to different imaging modes (imaging with direct or half-skip wave paths) according to the type of defects (point-like or extended crack-types defects)