370 research outputs found
Formulation of a 4-DoF torsion/bending element for the formfinding of elastic gridshells
International audienceThe paper presents a completely novel approach to model elastic gridshells with a 4-DoF element based on recent advances in the field of hair modelling [1]. This element, based on Kirchhoff's beam theory, can account for both bending and torsion behaviours. The reduction from 6 to 4 degrees of freedom is achieved with an appropriate curve framing introduce by R. Bishop [2]. The resulting model is fast and efficient. Its accuracy has been validated on test cases. It opens new outlooks for the design of elastic gridshells
Vers des machines exaflopiques vertes
National audienceMoving to exascale era can not be done without taking into account the energy consumption of such systems. In this paper, we wonder if the solutions found for the petascale era will still be available for the exascale era. We propose to adapt some of them within a green framework.Les superordinateurs ont connu une croissance rapide en particulier ces dernieÌres anneÌes. AÌ peine avons-nous franchi l'eÌchelle du petaflop que l'on s'inteÌresse deÌjaÌ aÌ concevoir des machines pouvant atteindre 1 exaflop par seconde et ce, afin d'eÌtre en mesure de satisfaire les besoins importants en terme de performances qu'expriment les scientifiques dans divers domaines. Cependant, pour concevoir des machines exaflopiques, il faut au preÌalable relever certains deÌfis dont le principal est d'eÌtre capable de reÌduire les importants couÌts de consommations eÌnergeÌtiques dans ces machines. Dans cet article, nous nous demandons si les solutions existantes pour reÌduire la consommation eÌnergeÌtique au niveau peÌta- flopique resteront valables aÌ l'eÌchelle exaflopique et dans quelles mesures il est possible de les adap- ter pour qu'elles puissent passer aÌ l'eÌchelle. Nous proposons eÌgalement des solutions nouvelles pour l'eÌchelle exaflopique, qui deÌbouchent sur une architecture verte pour les machines exaflopiques
Influence of Molecular Organization on the Electrical Characteristics of {\pi}-conjugated Self-assembled Monolayers
Two new thiol compounds with {\sigma}-{\pi}-{\sigma} structure were
synthesized and self-assembled on gold substrates. The morphology and the
structural characterization of SAMs assessed by infrared spectroscopy, contact
angle, XPS, electrochemistry and scanning tunneling microscopy (STM) show the
formation of monolayers. SAMs with a terthiophene (3TSH) core as conjugated
system are much better organized compared to those with a naphthalene
carbodiimide (NaphSH) core as demonstrated by the cyclic voltammetry and STM
studies. The surface concentration of 3TSH and NaphSH is respectively three and
six times lower than ordered SAMs of pure alkyl chains. A large number of I/V
characteristics have been studied either by STS measurements on gold substrates
or by C-AFM on gold nanodots. Transition Voltage Spectroscopy (TVS) was used to
clearly identify the transport in these partially organized monolayers. The
chemical nature of the conjugated system, donor for 3TSH and acceptor for
NaphSH, involves an opposite rectification associated to the asymmetrical
coupling of the molecular orbitals and the electrodes. The conductance
histograms show that the 3TSH junctions are less dispersed than those of NaphSH
junctions. This is explained by a better control of the molecular organization
in the molecular junctions.Comment: Full paper with supporting informatio
Panchromatic Study of the First Galaxies with Large ALMA Programs
Thanks to deep optical to near-IR imaging and spectroscopy, significant
progress is made in characterizing the rest-frame UV to optical properties of
galaxies in the early universe (z > 4). Surveys with Hubble, Spitzer, and
ground-based facilities (Keck, Subaru, and VLT) provide spectroscopic and
photometric redshifts, measurements of the spatial structure, stellar masses,
and optical emission lines for large samples of galaxies. Recently, the Atacama
Large (Sub) Millimeter Array (ALMA) has become a major player in pushing
studies of high redshift galaxies to far-infrared wavelengths, hence making
panchromatic surveys over many orders of frequencies possible. While past
studies focused mostly on bright sub-millimeter galaxies, the sensitivity of
ALMA now enables surveys like ALPINE, which focuses on measuring the gas and
dust properties of a large sample of normal main-sequence galaxies at z > 4.
Combining observations across different wavelengths into a single, panchromatic
picture of galaxy formation and evolution is currently and in the future an
important focus of the astronomical community.Comment: 4 pages, 2 figures. Submitted to Proceedings IAU Symposium No. 341,
201
Energy efficiency in HPC with and without knowledge of applications and services
International audienceThe constant demand of raw performance in high performance computing often leads to high performance systems' over-provisioning which in turn can result in a colossal energy waste due to workload/application variation over time. Proposing energy efficient solutions in the context of large scale HPC is a real unavoidable challenge. This paper explores two alternative approaches (with or without knowledge of applications and services) dealing with the same goal: reducing the energy usage of large scale infrastructures which support HPC applications. This article describes the first approach "with knowledge of applications and services'' which enables users to choose the less consuming implementation of services. Based on the energy consumption estimation of the different implementations (protocols) for each service, this approach is validated on the case of fault tolerance service in HPC. The approach "without knowledge'' allows some intelligent framework to observe the life of HPC systems and proposes some energy reduction schemes. This framework automatically estimates the energy consumption of the HPC system in order to apply power saving schemes. Both approaches are experimentally evaluated and analyzed in terms of energy efficiency
Structural Phase Transition and Superconductivity in 2H-BaGaGe with Buckled Honeycomb Layers
We report on the structural and superconducting properties of the
intermetallic compound BaGaGe. We find that this material undergoes a
structural second-order phase transition from the distorted AlB-type
structure (1H, = 4.3254(2) \r{A}, = 5.1078(3) \r{A}, P6/mmm) into the
CaIn-type structure (2H, = 4.3087(3) \r{A}, = 10.2117(6) \r{A},
P6/mmc) at a transition temperature of = 253 K. We find that
the structural phase-transition corresponds to a coherent buckling of the
honeycomb layers, which we can interpret as a disorder-to-order transition of
the atoms located within this layer. We show that the 2H-BaGaGe phase becomes
superconducting at a critical temperature of = 2.1 K. The bulk
nature of the superconductivity in 2H-BaGaGe is confirmed by means of specific
heat measurements, where we determine a value of /
= 1.59, which is close to the expected BCS value in the weak coupling limit
Natural plant diet impacts phenotypic expression of pyrethroid resistance in Anopheles mosquitoes
Success in reducing malaria transmission through vector control is threatened by insecticide resistance in mosquitoes. Although the proximal molecular mechanisms and genetic determinants involved are well documented, little is known about the influence of the environment on mosquito resistance to insecticides. The aim of this study was to assess the effect of plant sugar feeding on the response of Anopheles gambiae sensu lato to insecticides. Adults were fed with one of four treatments, namely a 5% glucose control solution, nectariferous flowers of Barleria lupulina, of Cascabela thevetia and a combination of both B. lupulina+C. thevetia. WHO tube tests were performed with 0.05% and 0.5% deltamethrin, and knockdown rate (KD) and the 24 h mosquito mortality were measured. Plant diet significantly influenced mosquito KD rate at both concentrations of deltamethrin. Following exposure to 0.05% deltamethrin, the B. lupulina diet induced a 2.5 fold-increase in mosquito mortality compared to 5% glucose. Species molecular identification confirmed the predominance of An. gambiae (60% of the samples) over An. coluzzii and An. arabiensis in our study area. The kdr mutation L1014F displayed an allelic frequency of 0.75 and was positively associated with increased phenotypic resistance to deltamethrin. Plant diet, particularly B. lupulina, increased the susceptibility of mosquitoes to insecticides. The finding that B. lupulina-fed control individuals (i.e. not exposed to deltamethrin) also displayed increased 24 h mortality suggests that plant-mediated effects may be driven by a direct effect of plant diet on mosquito survival rather than indirect effects through interference with insecticide-resistance mechanisms. Thus, some plant species may weaken mosquitoes, making them less vigorous and more vulnerable to the insecticide. There is a need for further investigation, using a wider range of plant species and insecticides, in combination with other relevant environmental factors, to better understand the expression and evolution of insecticide resistance
Detectors and cryostat design for the SuMIRe Prime Focus Spectrograph (PFS)
We describe the conceptual design of the camera cryostats, detectors, and
detector readout electronics for the SuMIRe Prime Focus Spectrograph (PFS)
being developed for the Subaru telescope. The SuMIRe PFS will consist of four
identical spectrographs, each receiving 600 fibers from a 2400 fiber robotic
positioner at the prime focus. Each spectrograph will have three channels
covering wavelength ranges 3800 {\AA} - 6700 {\AA}, 6500 {\AA} - 10000 {\AA},
and 9700 {\AA} - 13000 {\AA}, with the dispersed light being imaged in each
channel by a f/1.10 vacuum Schmidt camera. In the blue and red channels a pair
of Hamamatsu 2K x 4K edge-buttable CCDs with 15 um pixels are used to form a 4K
x 4K array. For the IR channel, the new Teledyne 4K x 4K, 15 um pixel,
mercury-cadmium-telluride sensor with substrate removed for short-wavelength
response and a 1.7 um cutoff will be used. Identical detector geometry and a
nearly identical optical design allow for a common cryostat design with the
only notable difference being the need for a cold radiation shield in the IR
camera to mitigate thermal background. This paper describes the details of the
cryostat design and cooling scheme, relevant thermal considerations and
analysis, and discusses the detectors and detector readout electronics
Référentiel de connaissances pour un numérique éco-responsable
Lâobjectif de ce document est de dĂ©finir un rĂ©fĂ©rentiel/socle de connaissances commun pour les enseignements sur le numĂ©rique responsable (impacts du numĂ©rique et comment les limiter1), Ă destination de formations en informatique ou dâautres filiĂšres incluant des cours dâinformatique.Nous cherchons Ă rĂ©pondre Ă la question suivante :Quelles connaissances devrait apporter une formation en informatique Ă des Ă©tudiantes et Ă©tudiants pour leur permettre dâapporter des rĂ©ponses aux enjeux environnementaux et sociĂ©taux dans leur vie professionnelle et citoyenne ?Ce document est donc focalisĂ© sur les impacts du numĂ©rique, mais certains aspects plus gĂ©nĂ©raux(enjeux environnementaux, contexte Ă©conomique...) sont nĂ©anmoins abordĂ©s car nĂ©cessaires Ă la comprĂ©hension des aspects informatiques.Ce rĂ©fĂ©rentiel vise Ă fournir des notions et rĂ©fĂ©rences utiles, mais nâa pas vocation Ă remplacer un cours
- âŠ