Autonomous Pareto Front Scanning using an Adaptive Multi-Agent System for Multidisciplinary Optimization

Multidisciplinary Design Optimization (MDO) problems can have a unique objective or be multi-objective. In this paper, we are interested in MDO problems having at least two conflicting objectives. This characteristic ensures the existence of a set of compromise solutions called Pareto front. We treat those MDO problems like Multi-Objective Optimization (MOO) problems. Actual MOO methods suffer from certain limitations, especially the necessity for their users to adjust various parameters. These adjustments can be challenging, requiering both disciplinary and optimization knowledge. We propose the use of the Adaptive Multi-Agent Systems technology in order to automatize the Pareto front obtention. ParetOMAS (Pareto Optimization Multi-Agent System) is designed to scan Pareto fronts efficiently, autonomously or interactively. Evaluations on several academic and industrial test cases are provided to validate our approach

Simulation et optimisation de systèmes hypersustentés d'avions civils équipés de dispositifs de contrôle des décollements

PARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Costs of public funds in project cost-benefit analysis

International audienceOver the long term, sometimes on the scale of several centuries, transport investments will shapethe fundamental character of the country, the quality of its environment and its ability to meet futurechallenges. This underscores the importance of making decisions in the most informed mannerpossible, making the best evaluation of the benefits they will provide and the costs they willengender, especially since their funding is largely based on public funds, a scarce resource ingeneral and even more so today.Project cost-benefit analysis (CBA) often makes use of parameters related to the public financesystem, which are designed to take into account imperfections in the tax structure and the shortfallof public resources. This paper discusses how to define, estimate and use for CBA the “opportunitycost of public funds”, which measures the inefficiency in the structure of the tax system. Itdiscusses also the methods for prioritising projects in times of limited budgets when, for a given taxstructure, tax revenue does not provide sufficient resources for public spending on all projects thatmerit it. To take into account that constraint, it suggests the introduction of a "scarcity cost ofpublic funds" coefficient, which applies to public spending, and which should be used together withthe opportunity cost of public funds when public funds available are insufficient to carry out allworthwhile projects.The opportunity cost depends on the tax structure, regardless of its level: as the distortive effect ofthese taxes increases (reducing the incentive for economic activity), so does the opportunity cost.The scarcity cost depends on the level of public funding for investment: as the difference betweenthe funds for investment and the volume of worthwhile investment increases, so does the scarcitycost. The opportunity cost applies to the project's expenditures and revenues; the scarcity cost onlyapplies to public expenditures.Methodology :Refering to Beaud(2013) we analyse the main sources of public revenues and their distortiveeffects, deriving analytical formulas first. Then, using statistical data for France and introducinginformed assumptions, we issues numerical estimations of distortion coefficients for each mainsource public revenue in France, and for each main type of public entity (each of these having itsown sources of revenues), among those the French state.The scarcity cost depends more on the balance between a level of budget constraint and the list andcosts of potential transport projects: an illustrative simulation is made so as to estimate an order ofmagnitude for the scarcity cost in France.The limits and extensions of these notions and methodologies are then discussed. Analyses on thepractical use of OCPF and SCPF does lead to cross political economy considerations withnormative economics, and compare methodologies used in several countries.Results :Numerical results indicate that the OCPF for the main sources of revenues range between 1,01 to2,2, the combined OCFP for the French state being close to 1,2. The scarcity cost is estimated to be0,05 when systemic risks are fully taken into account in project CBA, but comes out higher whenrisks are not fully taken into account in net present value estimations.The discussion drives to question other types of similar distortions, which do not necessarily relateto public funds, some of them leading to imperfect competition issues for instance. Practical advicefor the use of OCPF and SCPF at the project level and for programming, and their limits, are given

Modulation of the organic heterojunction behavior, from electrografting to enhanced sensing properties

International audienceThe energy barrier of an organic heterojunction built on ITO electrodes and made from a low conductive sublayer (Cu(F16Pc)) covered by a highly conductive semiconductor (LuPc2) is modulated by electrografting of organic layers before depositing the sublayer. Impedance spectroscopy clearly demonstrates the increase of the energy barrier at the ITO – sublayer interface. Additionally, the electrografting is a versatile and promising method for the tuning of heterojunctions. The I(V) characteristics of the heterojunctions are highly modified by the electrografting. The same electromodifications of electrodes carried out on LuPc2 resistors lead to a modification of their transport properties too. The effect of the grafting of four different aromatic moieties bearing electron-donating and electron-withdrawing substituents is studied. One important feature is that the sensing properties are highly improved compared to the unmodified devices. Thus, the electrografting of dimethoxybenzene doubles the relative response of the heterojunction towards 90 ppm NH3, as well as the sensitivity in the range 1–9 ppm. This electrografting allows attaining a limit of detection as good as 140 ppb. The modified heterojunctions favorably compete other conductometric transducers for the detection of ammonia, at room temperature and in a broad range of relative humidity

Autonomous Pareto Front Scanning using a Multi-Agent System for Multidisciplinary Optimization

International audienceMultidisciplinary Design Optimization (MDO) problems can have a unique objective or be multi-objective. In this paper, we are interested in MDO problems having at least two conflicting objectives. This characteristic ensures the existence of a set of compromise solutions called Pareto front. We treat those MDO problems like Multi-Objective Optimization (MOO) problems. Actual MOO methods suffer from certain limitations, especially the necessity for their users to adjust various parameters. These adjustments can be challenging, requiering both disciplinary and optimization knowledge. We propose the use of the Adaptive Multi-Agent Systems technology in order to automatise the Pareto front obtention. ParetOMAS (Pareto Optimization Multi-Agent System) is designed to scan Pareto fronts efficiently, autonomously or interactively. Evaluations on several academic and industrial test cases are provided to validate our approach

Optimisation multi-fidélité basée sur une approche Gappy-POD. Application à l'écoulement transonique autour de l'aile RAE-2822

International audienceL'optimisation de systèmes complexes fait largement appel à des méthodes de simulation très coûteuses. Dans cette optique, les méthodes de réduction de dimensionnalité ouvrent de nouvelles solutions. Les procédés de conception ingénieurs étant souvent intrinsèquement multi-fidélité, le couplage du potentiel de simplification physique de la décomposition orthogonale aux valeurs propres à des méthodes d'optimisation multi-fidélité est ici proposé. Ces méthodes seront appliquées à l'optimisation de l'aile RAE-2822 en écoulement transonique

Suivi du déplacement de brebis en environnement arboré par GPS différentiel (projet PARASOL)

National audienc

The origin of Listeria monocytogenes 4b isolates is signified by subproteomic profiling.

International audienceAmong the 13 known serovars of Listeria monocytogenes, strains exhibiting the serovar 4b are the most prevalently involved in epidemics of human listeriosis. The molecular reasons for the major involvement of serovar 4b strains in all major foodborne outbreaks in contrast to the lower prevalence of this serovar among food isolates remain indefinite. In order to provide further insight in the protein expression of L. monocytogenes 4b strains, the cytoplasmic and extracellular proteomes of L. monocytogenes 4b strains from different origins, i.e. environmental, clinical and asymptomatical carriage, were investigated by two-dimensional gel electrophoresis. Statistical hierarchical clustering analysis on subproteomic profiles clearly discriminated the strains according to their origin. Protein spots differentiating the subproteome patterns were identified using MALDI-TOF MS through their peptide mass fingerprint

Comparative Analysis of Extracellular and Intracellular Proteomes of Listeria monocytogenes Strains Reveals a Correlation between Protein Expression and Serovar▿ †

Listeria monocytogenes, the etiologic agent of listeriosis, remains a serious public health concern, with its frequent occurrence in food environments coupled with a high mortality rate. Among the 13 serovars, human listeriosis is mostly associated with the serovar 4b, 1/2b, and 1/2a strains. To investigate the diversity of L. monocytogenes, the intracellular and extracellular proteins of 12 strains were analyzed by two-dimensional gel electrophoresis. These strains had different origins, belonged to different serovars (4b, 1/2a, and 1/2b), and presented with different levels of virulence in chicken embryos. The clustering of the strains in two groups based on proteomic patterns is in agreement with the L. monocytogenes phylogenetic lineages. Statistical analysis did not allow for identification of proteins specific to the isolate origin or the virulence level of the strains, but 26 and 21 protein spots were shown to be significantly overexpressed and underexpressed, respectively, in the six strains of serovar 1/2a (lineage II) compared to strains of serovar 1/2b or 4b. Moreover, a penicillin-binding protein was specific for serovar 1/2b and two protein spots identified as a serine protease were specific to serovar 4b. These protein spots, identified through peptide mass fingerprinting using matrix-assisted laser desorption ionization-time of flight mass spectrometry, were essentially found in the extracellular proteome and may have uses as potential markers for serotyping and risk analysis