1,872 research outputs found
Disc volume properties from MRI in adolescent idiopathic scoliosis: correlation to surgical outcome
In young scoliotic patients, the post-operative consequence of spine fusion upon the free lower lumbar spine is one of the major concerns of the surgical treatment. The remodeling of free-motion segment and the role of discs below thoraco-lumbar fusions remains unknown. However, disc hydration and mass exchange flow between disc and vertebral body should play a significant role in the mechano-biology of the vertebral segment. Magnetic resonance imaging is relevant to study intervertebral discs in young scoliotic patients since related to hydration and non-radiant
Direct strain and slope measurement using 3D DSPSI
This communication presents a new implementation of DSPSI. Its main features
are 1. an advanced model taking into account the beam divergence, 2. the
coupling with a surface shape measurement in order to generalize DSPSI to
nonplanar surfaces 3. the use of small shear distance made possible using a
precise measurement procedure. A first application on a modified Iosipescu
shear test is presented and compared to classical DIC measurements
Direct strain and slope measurement using 2D DSPSI Title
Large variety of optical full-field measurement techniques are being
developed and applied to solve mechanical problems. Since each technique
possess its own merits, it is important to know the capabilities and
limitations of such techniques. Among these optical full-field methods,
interferometry techniques take an important place. They are based on
illumination with coherent light (laser). In shearing interferometry the
difference of the out of-plane displacement in two neighboring object points is
directly measured. Since object displacement does not result in interferometry
fringes, the method is suited for localization of strain concentrations and is
indeed used in industry for this purpose. Used quantitatively DSPSI possesses
the advantage over conventional out-of-plane displacement-sensitive
interferometry that only a single difference of the unwrapped phase map is
required to obtain flexural strains, thereby relieving problems with noise and
reduction in the field of view. The first publication on (DSPSI) was made in
1973, but the emergence of a system providing quantitative measurements is more
recent. This work aims to present the results of strain measurements using
digital speckle pattern shearing interferometry (DSPSI).Comment: Communication \`a la Conf\'erence M\'editerran\'eenne sur les
Mat\'eriaux Innovants et Applications -CIMA, Beyrouth, Liban-Mars 15-17,
2011; JM-CIMA.pd
Low Power Implementation of Non Power-of-Two FFTs on Coarse-Grain Reconfigurable Architectures
The DRM standard for digital radio broadcast in the AM band requires integrated devices for radio receivers at very low power. A System on Chip (SoC) call DiMITRI was developed based on a dual ARM9 RISC core architecture. Analyses showed that most computation power is used in the Coded Orthogonal Frequency Division Multiplexing (COFDM) demodulation to compute Fast Fourier Transforms (FFT) and inverse transforms (IFFT) on complex samples. These FFTs have to be computed on non power-of-two numbers of samples, which is very uncommon in the signal processing world. The results obtained with this chip, lead to the objective to decrease the power dissipated by the COFDM demodulation part using a coarse-grain reconfigurable structure as a coprocessor. This paper introduces two different coarse-grain architectures: PACT XPP technology and the Montium, developed by the University of Twente, and presents the implementation of a\ud
Fast Fourier Transform on 1920 complex samples. The implementation result on the Montium shows a saving of a factor 35 in terms of processing time, and 14 in terms of power consumption compared to the RISC implementation, and a\ud
smaller area. Then, as a conclusion, the paper presents the next steps of the development and some development issues
Spatial distribution of an eel population (Anguilla anguilla L.) in a small coastal catchments of northern Brittany (France). Consequences hydraulic works.
The Frémur is a 60 km2 catchment of Brittany where many hydraulic works (dams, weirs, gauging structures, etc.) have reduced the recruitment by elvers and glass eels since at least 50 years. In 1992, an eel lift was built on the main dam (14 m high) and in 1996, two other dams (5 m high) located downstream were equipped with eel passes to improve upstream migration. In 1995, before the construction of the passes, eel population parameters (density, biomass and size distribution) were assessed at the scale of the whole watershed by electrofishing (removal method) in 33 stations. The average biomass was high (19 g/m2 ) despite the numerous physical obstructions. However, there was an accumulation of eels downstream many hydraulic works and very low densities immediately upstream. Moreover, downstream the first obstruction, at 2 km from the sea, the population is dominated by boot lace eels and elvers (< 100 mm), whereas this size class is absent in upstream reaches. These results suggest that the standing capacity of the watershed is not reached and that the population could be enhanced in the next years by the recently installed eel passes
Ramsey's Principle Re-Situated
This paper is about Ramsey's Principle, according to which a belief's truth-conditions are those that guarantee the success of an action based on that belief whatever the underlying motivating desires. Some philosophers have argued that the Principle should be rejected because it leads to the apparently implausible consequence that any failure of action is the result of some false belief on the agent's part. There is a gap between action and success that cannot be bridged by the agent's cognitive state. At best, the Principle should be relativized to circumstances. We show on the contrary that when the Principle is properly understood, it does not amount to “overburdening” belief. We exploit an analogy between knowledge and action in order to show that intentional action is a source of knowledge relative to a set of beliefs whose collective truth guarantees the success of the action. It does not follow that the agent is explicitly representing all possible obstacles to her action. Most of the relevant beliefs are implicit, in the sense that if they were to be formed, they would be directly or indirectly justified by the agent's experience of acting
Ancenis – Couvent des Ursulines
Les trois sondages pratiqués dans la partie ruinée (chœur des moniales et sa cour attenante) de la chapelle du couvent des Ursulines de La Davrays à Ancenis ont permis d’observer les niveaux d’installation et de sols de travail des bâtiments construits à partir de 1643. Deux massifs quadrangulaires, très vraisemblablement destinés à soutenir des poteaux de charpente, ont été mis au jour à la limite entre l’abside et la travée droite du chœur, il s’agit d’aménagements tardifs probablement liés..
Les Sables-d’Olonne – Abbaye Sainte-Croix
Les trois sondages implantés dans la cour du cloître de l’ancienne abbaye bénédictine Sainte-Croix des Sables-d’Olonne (aujourd’hui musée) ont permis d’observer la succession des niveaux de remblais et de préparations installés sur les dépôts sableux et vaseux recouvrant le substrat rocheux pour permettre la construction du couvent sur ces terrains bas et marécageux. Un abondant mobilier y a été recueilli comprenant essentiellement de la vaisselle et des déchets de cuisine ainsi que plusieurs..
Les Lucs-sur-Boulogne – Val de Bourgneuf, RD937, 1 et 2
Le diagnostic mené au nord-ouest du village de Bourgneuf, commune des Lucs-sur-Boulogne, a permis de mettre au jour un enclos rectangulaire allongé comportant une entrée sur son côté sud-est (dimensions minimales : 45 m sur 70 m) ; le rare mobilier recueilli suggère de l’attribuer au Moyen Âge. De nombreux éléments de plusieurs réseaux parcellaires ont également pu être observés, la plupart peuvent être mis en relation avec les limites figurant sur le cadastre napoléonien (1837) et avec le vi..
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