Éditeur(s) : HAL CCSD
Résumé : International audience
Semi-volatile organic compounds (SVOCs) partition indoors between the gas phase, airborne particles, settled dust, and other surfaces. Unknown concentrations of SVOCs in the gas phase (Cg) can be predicted from their measured concentrations in airborne particles. In previous studies, the prediction of Cg depended largely on choosing a specific equation for the calculation of the particle/gas partition coefficient. Moreover, the prediction of Cg is frequently performed at a reference temperature rather than the real indoor temperature. In this paper, a probabilistic approach based on Monte Carlo simulation was developed to predict the distribution of SVOCs' Cg from their concentrations in airborne particles at the target indoor temperature. Moreover, the distribution of the particle/gas partition coefficient of each SVOC at the target temperature was used. The approach was validated using two measured datasets in the literature: the predicted Cg from concentrations measured in airborne particles and the measured Cg were generally of the same order of magnitude. The distributions of the Cg of 66 SVOCs in the French housing stock were then predicted. The SVOCs with the highest median Cg, ranging from 1 ng/m3 to > 100 ng/m3, included 8 phthalates (DEP, DiBP, DBP, DEHP, BBP, DMP, DiNP, and DMEP), 4 polycyclic aromatic hydrocarbons (fluorene, phenanthrene, fluoranthene, and anthracene), 2 alkylphenols (4-tert-butylphenol and 4-tert-octylphenol), 2 synthetic musks (galaxolide and tonalide), tributyl phosphate, and heptachlor. The nationwide, representative, predicted Cg values of SVOCs are frequently of the same order of magnitude in Europe and North America, whereas these Cg values in Chinese and Indian dwellings and the Cg of polybrominated diphenyl ethers in U.S. dwellings are generally higher. © 2016 Elsevier B.V.
Science of the Total Environment

hal-01467547
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01467547
DOI : 10.1016/j.scitotenv.2016.10.074
PUBMED : 27788447

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
The dynamic model of plant growth GreenLab describes plant architecture and functional growth at the level of individual organs. Structural development is controlled by formal grammars and empirical equations compute the amount of biomass produced by the plant, and its partitioning among the growing organs, such as leaves, stems and fruits. The number of organs initiated at each time step depends on the trophic state of the plant, which is evaluated by the ratio of biomass available in plant to the demand of all the organs. The control of the plant organogenesis by this variable induces oscillations in the simulated plant behaviour. The mathematical framework of the GreenLab model allows to compute the conditions for the generation of oscillations and the value of the period according to the set of parameters. Two case-studies are presented, corresponding to emergence of oscillations associated to fructification and branching. Similar alternating patterns are commonly reported by botanists. In this article, two examples were selected: alternate patterns of fruits in cucumber plants and alternate appearances of branches in Cecropia trees. The model was calibrated from experimental data collected on these plants. It shows that a simple feedback hypothesis of trophic control on plant structure allows the emergence of cyclic patterns corresponding to the observed ones.
ISSN: 0973-5348

hal-00780592
https://hal-ecp.archives-ouvertes.fr/hal-00780592
https://hal-ecp.archives-ouvertes.fr/hal-00780592/document
https://hal-ecp.archives-ouvertes.fr/hal-00780592/file/Mathieu_2012_Published_mmnp201276p47.pdf
DOI : 10.1051/mmnp/20127603

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Numerical programs for simulating flow and reactive transport in porous media is essential for predicting reservoir properties related to CO2 sequestration performance, subsurface storage and risk assessment. In this paper we solve the Navier Stokes' equation using finite difference method, on a simulated porous rock structure, to study the velocity distribution of fluid flowing through it under a constant pressure gradient. A reactive solute carried through the fluid is allowed to interact with the minerals in the rock. This chemical reaction dissolves the mineral which changes the rock structure thus affecting its flow properties. These changes of flow properties are studied with variation in reactive solute concentration and pressure field. The different mechanisms of dissolution responsible for the variation of flow properties for the different parameters is predicted. Before the onset of homogeneous dissolution, variation in porosity follows a power-law behaviour with change in permeability when the latter is scaled by the concentration of the reactive species. The simulation results are compared with available experimental data and found to give a reasonable match.
ISSN: 0022-1694

hal-00757760
https://hal.archives-ouvertes.fr/hal-00757760
DOI : 10.1016/j.jhydrol.2012.05.024

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : We propose and we justify a Monte-Carlo algorithm which solves a spatially homogeneous kinetic equation of Boltzmann type that models the fusion reaction between a deuterium ion and a tritium ion, and giving an α particle and a neutron. The proposed algorithm is validated with the use of explicit solutions of the kinetic model obtained by replacing the fusion cross-section by a Maxwellian cross section.
ISSN: 1270-900X

hal-00689821
https://hal.archives-ouvertes.fr/hal-00689821
https://hal.archives-ouvertes.fr/hal-00689821/document
https://hal.archives-ouvertes.fr/hal-00689821/file/proc_versionHAL.pdf

Éditeur(s) : HAL CCSD University of Waterloo
Résumé : International audience
We study several families of solutions to equations of the form (n) = An + B(n), where B is a function that may depend on properties of n.
ISSN: 1530-7638

hal-00761663
https://hal.univ-antilles.fr/hal-00761663
https://hal.univ-antilles.fr/hal-00761663/document
https://hal.univ-antilles.fr/hal-00761663/file/hasler21.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Field observations of highly porous and permeable sandstone in the Orange area (S-E Basin, France) show that networks of shear-enhanced compaction bands can form in a contractional regime at burial depths of about 400 m ± 100 m. These bands show equal compaction and shear displacements, are organized in conjugate and densely distributed networks, and are restricted to the coarse-grained (mean grain diameter of 0.6 ± 0.1 mm) and less porous (porosity of 26 ± 2%) sand layers. The bands are crush microbreccia with limited grain comminution and high grain microfracture density. They show reductions of permeability (mD) ranging from 0 to little more than 1 order of magnitude. They show no control on the alteration products related to meteoric water flow, which suggests that these shear-enhanced compaction bands have no or only negligible influence on subsurface fluid flow. Their selective occurrence and small (20%) reduction in transmissibility in densely populated layers prevented them from compartmentalizing the sandstone reservoirs. A comparison with compaction-band populations in the Navajo and Aztec sandtsones (western U.S.) emphasizes the role of burial depth and the presence of chemical compaction processes for the sealing potential of deformation bands.
ISSN: 0191-8141

hal-00807309
https://hal.archives-ouvertes.fr/hal-00807309
DOI : 10.1016/j.jsg.2012.11.008

Éditeur(s) : HAL CCSD Springer Verlag (Germany)
Résumé : International audience
The Michaelis-Menten enzymatic reaction is sufficient to perceive many subtleties of network modeling, including the concentration and time scales separations, the formal equivalence between bulk phase and single-molecule approaches, or the relationships between single-cycle transient probabilities and steady state rates. Twelve methods proposed by different authors and yielding the same famous Michaelis-Menten equation, are selected here to illustrate the kinetic and probabilistic use of rate constants and to review basic techniques for handling them. Finally, the general rate of an ordered multistep reaction, of which the Michaelis-Menten reaction is a particular case, is deduced from a Markovian approach.
ISSN: 0259-9791

hal-00920806
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00920806
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00920806v2/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00920806/file/12MM.pdf
ARXIV : 1312.5468

Résumé : Dans le cas des DOM, singulièrement la Guadeloupe, qui sont à l'aube de l'expérimentation de réformes profondes de politiques économiques, l'élaboration d'un outil de simulation macroéconomique tel qu'un MEGC apparaît naturellement comme une exigence plus que souhaitable. Ce recours à la construction de modèles spécifiques pour les DOM est en parfaite cohérence avec l'une des principales conclusions du rapport d'information diligenté par le Sénat aux lendemains de la crise sociale du début de l'année 2009. Les appels à projet de la Commission europèenne et du Ministère de l'Outre-mer vont justement dans le sens de pallier celte carence puisque la politique économique des RUP de façon générale est conduite à vue sans aucun outil d'investigation ex ante. Nous avons conçu plusieurs modèles. Parmi eux, CloDyn est le premier modèle macroéconomique pour les DOM à vocationopérationnelle. Composée de plus de 2000 équations, ce modèle d'équilibre général calculable tient compte de nombreuses rigidités sur les marchés des biens et services et du travail et se décline sous deux versions: statique et dynamique. Les élasticités ont fait l'objet d'estimations économétriques. Il tient compte de nombreuses spécificités tant au niveau de la fiscalité de ces régions (octroi de mer, taxe sur les carburants, subventions à l'exportation) que du coût des facteurs (exonérations des charges sur les bas salaires, sur rémunératio des fonctionnaires). Il repose sur une formalisation des mécanismes en oeuvre dans ces économies que nous avons appelé le DOM disease pour expliquer les dysfonctionnements persistants sur le plan macroéconomique.
In the case of the French overseas regions, particularly of Guadeloupe, which are just beginning to experiment with economic policies radical reforrns, the development of a macroeconomic simulation tool such as a CGE model appears naturally as a highly desirable requirement. The use of the construction of specifie models for DOM is fully consistent with a major finding of the report commissioned by the Senate in the aftermath of the social crisis of the early 2009. As a malter of facts, the purpose of the calls for project initiated by the European Commission and the Ministry of Overseas is to remedy this deficiency, since the RUP economie policy is generally to conduct no investigation tool ex ante. We designed several models. Among them, CloDyn is the first operational DOM-based macroeconomic rnodel. Composed of more than 2000 equations, this computable general equilibrium model takes into account many rigidities in the markets for goods and services and labor and is available in two versions: static and dynamic. Elasticities have been econometrically estimated. lt rests on many features of both taxation (dock dues, fuel tax, export subsidies) and the cost factors (exemption from charges on low wages, remuneration of civil servants). Il is based on a formalization of the mechanisms at work in these economies we calied the DOM disease to explain the persistent failures in such economies. lt also evaluates the monetary poverty among households with the use of a block of microsimulation model and we allow a profane in GAMS to use this tool and conduct its own analytical work thanks to a user friendly interface.

http://www.theses.fr/2011AGUY0411/document

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Various types of genome and gene similarity networks along with their characteristics have been increasingly used for retracing different kinds of evolutionary and ecological relationships. Here, we present a new polynomial time algorithm and the corresponding software (BRIDES) to provide characterization of different types of paths existing in evolving (or augmented) similarity networks under the constraint that such paths contain at least one node that was not present in the original network. These different paths are denoted as Breakthroughs , Roadblocks, Impasses, Detours, Equal paths, and Shortcuts. The analysis of their distribution can allow discriminating among different evolutionary hypotheses concerning genomes or genes at hand. Our approach is based on an original application of the popular shortest path Dijkstra's and Yen's algorithms.
ISSN: 1932-6203

Droits : http://creativecommons.org/licenses/by/
hal-01361753
http://hal.upmc.fr/hal-01361753
http://hal.upmc.fr/hal-01361753/document
http://hal.upmc.fr/hal-01361753/file/journal.pone.0161474.PDF
DOI : 10.1371/journal.pone.0161474

Éditeur(s) : HAL CCSD
Résumé : International audience
In the paper the following mixed equilibrium problem in a Hilbert space is considered: find x 2 C such that F(x, x)+hG(x), x−xi 0, 8x 2 C, where C is a nonempty convex closed subset of a real Hilbert space. For its solution a version of the proximal approach is studied. The general proximal method always includes a quadratic term of the kind |x−xn|2, which provides a process of transition from a point xn to a point xn+1. The authors replace this quadratic term by its linearization. Thus, they obtain a method of the kind F(xn+1, x)+hG(xn)+ −1(h 0(xn+1)−h 0(xk)), x−xn+1i 0, 8x 2 C, where h0 is the derivative of a given function on C. It is proved that if the function F(x, y) is monotone and convex in y for any x, F(x, x) = 0, and the operator G(x) is co-coercive, then the method weakly converges in a real Hilbert space to an equilibrium solution. Note that this result will also be true if the co-coercive condition is replaced by a monotonicity property. The Tikhonov regularization method (in the absence of disturbances and calculating auxiliary solutions approximately) is justified and its weak convergence in a Hilbert space is proved. It is known that the proximal method can always be interpreted as an implicit discret approximation of some differential equation or inclusion. Therefore the authors consider a differential inclusion for the extreme mapping. Permitting "-approximation for the function F(x, y) by means of a parametric family F(x, y, ") and assuming the strong monotonicity of the operator @F(x, y, ") (it is a very strong condition), the authors prove the convergence of the trajectory of the differential inclusion to an equilibrium solution.
Ill-posed variational problems and regularization techniques

hal-00773204
https://hal.univ-antilles.fr/hal-00773204

Éditeur(s) : HAL CCSD Elsevier
Résumé : The correct characterization of the effective reactive transport dynamics is an important issue for modeling reactive transport on the Darcy scale, specifically in situations in which reactions are localized, that is when different reactions occur in different portions of the porous medium. Under such conditions the conventional approach of homogenizing only the porous medium chemistry is not appropriate. We consider here reactive transport in a porous medium that is characterized by mass transfer between a mobile and a distribution of immobile regions. Chemical and physical heterogeneities are reflected by distributions of kinetic reaction rate constants and residence times in the immobile zones. We derive an effective reactive transport equation for the mobile solute that is characterized by non-local physical mass transfer and reaction terms. Specifically, chemical heterogeneity is upscaled in terms of a reactive memory function that integrates both chemical and physical heterogeneity. Mass transfer limitations due to physical heterogeneity yield effective kinetic rate coefficients that can be much smaller than the volumetric average of the local scale coefficients. These results help to explain and quantify the often reported discrepancy between observed field reaction rate constants and the ones obtained under well mixed laboratory conditions. Furthermore, these results indicate that transport under physical and chemical heterogeneity cannot be upscaled separately.
ISSN: 0169-7722

hal-00617674
https://hal.archives-ouvertes.fr/hal-00617674
DOI : 10.1016/j.jconhyd.2010.06.002

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
Individuals can play different roles in maintaining connectivity and socialcohesion in animal populations and thereby influence population robustnessto perturbations.We performed a social network analysis in a reef shark populationto assess the vulnerability of the global network to node removal underdifferent scenarios. We found that the network was generally robust to theremoval of nodes with high centrality. The network appeared also highlyrobust to experimental fishing. Individual shark catchability decreased as afunction of experience, as revealed by comparing capture frequency and sitepresence. Altogether, these features suggest that individuals learnt to avoidcapture, which ultimately increased network robustness to experimentalcatch-and-release. Our results also suggest that some caution must be takenwhen using capture–recapture models often used to assess population sizeas assumptions (such as equal probabilities of capture and recapture) maybe violated by individual learning to escape recapture.
EISSN: 1471-2954

hal-01561754
https://hal-univ-perp.archives-ouvertes.fr/hal-01561754
DOI : 10.1098/rsbl.2016.0824

Éditeur(s) : HAL CCSD
Résumé : International audience
The published literature related to distributed parameter systems theoryis quite large, and it is not feasible in a single book to give a detailedreview on the wide historical development of all of it. Our choice of whatto cover was motivated by the following consideration. Since distributedparameter systems evolve in time and space, the research investigationson their analysis and control focus on considering the whole system domainfor any study. We feel strongly that within this research field, animportant consideration was missing; that of considering that the systemmay give raise to prescribed subdomains (regions) where one has toachieve an objective. This is the case of so many applications rangingfrom engineering to life sciences. For that reason, covering classical prerequisitein analysis and control areas, we have devoted the book to theextension of the classical distributed parameter results to regional ones.Students of mathematics do not come into contacts with distributedparameter systems during their classes. They are introduced to themwhen they start research and often they are influenced by the knowledgeand the advice of experimented scientists. This was our case at the verybeginning of these research investigations in the mid 70’s. We would liketo express our special thanks to many of them and mainly late ProfessorAnthony J. Pritchard (University of Warwick, GB) and late Professor J.L. Lions (College de France) who were so encouraging in front of our determinationin driving an academic carrier. We also express our thanksto our co-workers and research students. We wish to acknowledge thefeedback from all those who took courses based on various parts of thisbook.This book may be used by graduate students in mathematics, engineering,physics, and even by students from other fields such as life orenvironmental sciences. This book may also be used as an informationvi Avant-propossource for researchers and education professionals. We assume that thereaders already know the basic concepts of analysis and control of distributedparameter systems.
https://hal.archives-ouvertes.fr/hal-01297261

ISBN : 978-2-35412-140-2
hal-01297261
https://hal.archives-ouvertes.fr/hal-01297261

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
We conducted triaxial compression experiments to investigate the effects of pressure, temperature and strain rate on the rheology of talc rocks. The tests were carried out at T from 25 to 860 degrees C, P from 0.1 to 300 MPa, and <(epsilon) over dot> from 0.3 to 30 x 10-5 s(-1). In addition to being very weak, there are other important differences between the mechanical behavior of talc and that of most other silicates. Deformation at all temperatures up to dehydration was accommodated by a combination of crystal plasticity, frictional sliding, and cataclasis. A transition from localized to distributed deformation occurred at P = 300 MPa and T = 400 degrees C, but this transition is ill-defined as both distributed and localized deformation were observed at P = 300 MPa and T = 600 degrees C. Unlike most silicates, both the coefficient of internal friction and the coefficient of (sliding) friction are very low and nearly equal to each other. Temperature enhances plastic deformation (kinking), and inter- and intra-granular microcracks are observed parallel to the (001) planes at all conditions. Voids are created by delamination along (001) planes at kink-band boundaries. Full crystal plasticity was not achieved under any of the conditions tested, i.e., the von Mises criterion was never satisfied. However, the strength of the aggregates remained much less than the confining pressure. These unusual properties are likely a manifestation of the pronounced mechanical anisotropy of talc at the grain scale. At T >= 750 degrees C dehydration is observed, but only along shear zones. These results suggest that feedbacks between deformation and reaction kinetics could control fluid flow in fault zones. The presence of talc can promote significant weakening and strain localization in the oceanic lithosphere, the subducting plate and the overlying mantle wedge. (c) 2008 Elsevier B.V. All rights reserved.
ISSN: 0012-821X

hal-00492706
https://hal.archives-ouvertes.fr/hal-00492706
DOI : 10.1016/j.epsl.2008.02.004

Éditeur(s) : HAL CCSD
Résumé : We provide a systematic study of sesquilinear hermitian forms and a new proof of the calculus of some exponential sums defined with quadratic hermitian forms. The computation of the number of solutions of equations such as Tr(f(x)+v.x)=0 or Tr(f(x))=a allows us to construct codes and to obtain their parameters.
https://hal.univ-antilles.fr/hal-00767443

hal-00767443
https://hal.univ-antilles.fr/hal-00767443
ARXIV : math/0111191

Éditeur(s) : HAL CCSD
Résumé : While often criticized, independence remains the ultimate criterion for evaluating board composition, whether for regulators or shareholder activists. In this study, we examine the relationship between board independence and firm operating performance in a panel of French listed companies, paying particular attention to heterogeneity and endogeneity concerns. We take advantage of an original database, with a time-series dimension that can be used to mitigate heterogeneity and dynamic endogeneity issues through GMM estimators. In addition, this database can be disaggregated at the individual (director) level. This design enables us to introduce firm fixed effects and individual fixed effects in (firm) performance equations, thereby controlling for heterogeneity at the firm and individual levels. To our knowledge, this is the first paper so far to provide a systematic account on this issue for France. Our main result is to document a significant negative relationship between accounting performance and the independence status (irrespective of the person). This result supports the argument of an information gap suffered by independent board members, as developed by Adams and Ferreira (2007).
https://hal.archives-ouvertes.fr/hal-00919408

hal-00919408
https://hal.archives-ouvertes.fr/hal-00919408
https://hal.archives-ouvertes.fr/hal-00919408v2/document
https://hal.archives-ouvertes.fr/hal-00919408/file/cahier_de_recherche_2014-01.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
This article is devoted to the presentation of a multilevel method using finite differences that is well adapted for solving Stokes and Navier-Stokes problems in primitive variables. We use Uzawa type algorithms to solve the saddle point problems arising from spatial discretization by staggered grids and a semi-explicit temporal scheme. By means of a new change of basis operator, the two-dimensional velocity and pressure fields of an M.A.C mesh are gathered in a hierarchical order, into several grids preserving the M.A.C property on each of them. These new hierarchical unknowns, called Staggered Incremental Unknowns (SIU), allow us to develop techniques which reduce the cost of the resolution of either Stokes or generalized Stokes problems. An experimental estimation of the condition number of the inner matrix is given, and justifies the preconditioning effect of the staggered incremental unknowns.
ISSN: 0168-9274

hal-00770268
https://hal.univ-antilles.fr/hal-00770268
DOI : 10.1016/S0168-9274(99)00044-6

Éditeur(s) : HAL CCSD
Résumé : International audience
Starting from a description of various generalized function algebras based on sequence spaces, we develop the general framework for considering linear problems with singular coefficients or non linear problems. Therefore, we prove functorial properties of those algebras and show how weak equalities, in the sense of various associations, can be described in this setting.
International Journal of Mathematics and Mathematical Sciencess

hal-00761083
https://hal.univ-antilles.fr/hal-00761083
https://hal.univ-antilles.fr/hal-00761083/document
https://hal.univ-antilles.fr/hal-00761083/file/0210249v1.pdf

Éditeur(s) : HAL CCSD Tsing Hua University
Résumé : International audience
This paper deals with variational inclusions of the form : $0in varphi(z)+F(z)$ where $varphi$ is a single-valued function admitting a second order Fréchet derivative and $F$ is a set-valued map from $R^q$ to the closed subsets of $R^q$. In order to approximate a solution $bar z$ of the previous inclusion, we use an iterative scheme based on a multipoint method. We obtain, thanks to some semistability properties of $bar z$, local superquadratic or cubic convergent sequences
ISSN: 1607-2510

hal-00728816
https://hal.archives-ouvertes.fr/hal-00728816

Éditeur(s) : HAL CCSD Elsevier
Résumé : Water molecules play a fundamental role in the physics of slow crack propagation in glasses. It is commonly understood that, during stress-corrosion, water molecules that move in the crack cavity effectively reduce the bond strength at the strained crack tip and, thus, support crack propagation. Yet the details of the environmental condition at the crack tip in moist air are not well determined. In a previous work, we reported direct evidence of the presence of a 100 nm long liquid condensate at the crack tip in fused silica glass during very slow crack propagation (10(-9)-10(-10) m/s). These observations are based on in situ AFM phase imaging techniques applied on DCDC glass specimens in controlled atmosphere. Here, we discuss the physical origin of the AFM phase contrast between the liquid condensate and the glass surface in relation to tip-sample adhesion induced by capillary bridges. We then report new experimental data on the water condensation length increase with relative humidity in the atmosphere. The measured condensation lengths were much larger than what predicted using the Kelvin equation and expected geometry of the crack tip.
ISSN: 0022-3093

hal-00412153
https://hal.archives-ouvertes.fr/hal-00412153
DOI : 10.1016/j.jnoncrysol.2007.06.090