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Marseille, France

Georget E.,Aix - Marseille University | Diaby F.,Polytechnic School | Abdeddaim R.,Aix - Marseille University | Sabouroux P.,Aix - Marseille University
8th European Conference on Antennas and Propagation, EuCAP 2014 | Year: 2014

This A multiple configuration of segmented coaxial cell is presented to measure the electromagnetic characteristics of different states of materials. These measurements are possible thanks to a sample holder. The processing of measurement is based on a well-known method, the reflection/transmission method. In this paper, we present a result for solid, flexible material, granular material and liquid. © 2014 European Association on Antennas and Propagation. Source


Batygin K.,California Institute of Technology | Brown M.E.,California Institute of Technology | Betts H.,Polytechnic School
Astrophysical Journal Letters | Year: 2012

Over the last decade, evidence has mounted that the solar system's observed state can be favorably reproduced in the context of an instability-driven dynamical evolution model, such as the "Nice" model. To date, all successful realizations of instability models have concentrated on evolving the four giant planets onto their current orbits from a more compact configuration. Simultaneously, the possibility of forming and ejecting additional planets has been discussed, but never successfully implemented. Here we show that a large array of five-planet (two gas giants + three ice giants) multi-resonant initial states can lead to an adequate formation of the outer solar system, featuring an ejection of an ice giant during a phase of instability. Particularly, our simulations demonstrate that the eigenmodes that characterize the outer solar system's secular dynamics can be closely matched with a five-planet model. Furthermore, provided that the ejection timescale of the extra planet is short, orbital excitation of a primordial cold classical Kuiper Belt can also be avoided in this scenario. Thus, the solar system is one of many possible outcomes of dynamical relaxation and can originate from a wide variety of initial states. This deems the construction of a unique model of solar system's early dynamical evolution impossible. © 2012. The American Astronomical Society. All rights reserved. Source


Leceta I.,University of the Basque Country | Guerrero P.,University of the Basque Country | Cabezudo S.,Polytechnic School | De La Caba K.,University of the Basque Country
Journal of Cleaner Production | Year: 2013

A comparative environmental assessment between two different food packaging systems was carried out: a commercial food packaging film based on polypropylene (PP) and a new biodegradable chitosanbased film developed in our labs. The environmental load of chitosan-based films in different life cycle stages was studied and compared with the one of conventional PP films currently used as food packaging. The functional unit in this study was 1 m2 of packaging film. The studied system includes three main stages: material extraction, film manufacture, and end of life. Results showed that PP films have higher impact than chitosan-based films in carcinogens and in fossil fuels impact categories. The environmental burden associated to carcinogens is mainly due to the end of life stage, while the impact related to fossil fuels is owing to the extraction of PP. On the contrary, chitosan-based films have higher environmental load in respiratory inorganics, land use, and minerals categories. Environmental load associated to respiratory inorganics is mostly related to the acetic acid used in the film manufacture and, in a more significant way, to the hydrochloric acid used in the raw material extraction, which is also responsible for the impact in minerals category. In addition, the main responsible for the impact in land use category is glycerine, considered as a by-product from biodiesel, used in the film manufacture stage. © 2012 Elsevier Ltd. All rights reserved. Source


Mohan N.,California Institute of Technology | Cheng J.,Polytechnic School | Greer J.R.,California Institute of Technology | Needleman A.,University of North Texas
Journal of Applied Mechanics, Transactions ASME | Year: 2013

Motivated by a model that qualitatively captured the response of vertically aligned carbon nanotube (VACNT) pillars in uniaxial compression, we consider the uniaxial tensile response of a class of compressible elastic-viscoplastic solids. In Hutchens et al. ["Analysis of Uniaxial Compression of Vertically Aligned Carbon Nanotubes," J. Mech. Phys. Solids, 59, pp. 2227-2237 (2011), Erratum 60, 1753-1756 (2012)] an elastic viscoplastic constitutive relation with plastic compressibility, plastic non-normality, and a hardening-softeninghardening hardness function was used to model experimentally obtained uniaxial compression data of cylindrical VACNT micropillars. Complex deformation modes were found in uniaxial compression, which include a sequential buckling-like collapse of the type seen in experiments. These complex deformation modes led to the overall stress-strain signature of the pillar not being of the same form as the input material hardness function. A fundamental question that motivates exploring the deformation of this class of materials-both experimentally and theoretically-is how to extract the intrinsic material response from simple tests. In this study we explore the relation between the input material response and the overall stress strain behavior in uniaxial tension using the constitutive framework of Hutchens et al. A simple one-dimensional analysis reveals the types of instability modes to be expected. Dynamic, finite deformation finite element calculations are carried out to explore the dependence of diffuse necking, localized necking, and propagating band deformation modes on characteristics of the hardness function. Attention is devoted to uncovering implications for obtaining intrinsic material properties of complex hierarchical structures; for example, vertically aligned carbon nanotubes (VACNTs), from uniaxial tension experiments. Copyright © 2013 by ASME. Source


Vasquez E.G.,Polytechnic School | Carvalho L.F.B.,IVIG | Leite da Fonseca I.C.,IVIG | Vasconcelos de Freitas M.A.,IVIG | Pinguelli Rosa L.,IVIG
WIT Transactions on Ecology and the Environment | Year: 2012

In order to adapt densely packed cities to climate change, there is a pressing need for the adoption of techniques that contribute to the sustainability of constructions and, therefore, of the cities themselves, so that they become more appropriate places to enable their citizens to live and work. Indeed, adopting techniques for greening built-up environments and making use of non-energyintensive construction technologies has proven to be an environmentally friendly and energetically efficient alternative, enhancing the micro-climate of adapted buildings and the meso-climate of the built up environment, creating ecologically appropriate alternatives for renewal of areas vulnerable to degradation and the expansion of sustainable newly constructed areas. In this context, with the support of the Rio de Janeiro State Research Funding Agency (FAPERJ), a practical experiment is currently underway at the Federal University of Rio de Janeiro (UFRJ) involving the application of naturation. This is a practical experiment that consists of applying vegetation to constructed surfaces using the COMPEC brick, which is comprised of organic and inorganic matter derived from solid urban waste. The aim is to evaluate energy and thermal comfort aspects by measuring the potential for energy conservation and efficiency gains when compared with conventional building materials. At present, 3 prototypes measuring 25m2 each are being built with conventional and ecological materials: Prototype 1 (slab covering made of concrete and walls made of ceramic brick), Prototype 2 (slab covering made of concrete and walls made of COMPEC bricks) and Prototype 3 (slab covering naturated and walls made of ceramic bricks), into which heat-sensing equipment will be installed internally. The methodology of this experiment calls for monitoring the thermal behavior of the materials employed, analyzing and comparing each prototype, as well as calculating the greenhouse gas emissions of the materials employed. The purpose of all this is to see whether the resulting data corroborates the hypothesis that it is possible to improve the thermal comfort of buildings via the application of naturation, as well as to reduce greenhouse gas emissions by using and recycling solid urban waste. © 2012 WIT Press. Source

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