376 research outputs found

    Analogical Proportions and Multiple-Valued Logics

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    National audienceRecently, a propositional logic modeling of analogical proportions, i.e., statements of the form “A is to B as C is to D”, has been proposed, and has then led to introduce new related proportions in a general setting. This framework is well-suited for analogical reasoning and classification tasks about situations described by means of Boolean properties. There is a clear need for extending this approach to deal with the cases where i) properties are gradual ; ii) properties may not apply to some situations ; iii) the truth status of a property is unknown. The paper investigates the appropriate extension in each of these three cases

    Model Reduction for Multiscale Lithium-Ion Battery Simulation

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    In this contribution we are concerned with efficient model reduction for multiscale problems arising in lithium-ion battery modeling with spatially resolved porous electrodes. We present new results on the application of the reduced basis method to the resulting instationary 3D battery model that involves strong non-linearities due to Buttler-Volmer kinetics. Empirical operator interpolation is used to efficiently deal with this issue. Furthermore, we present the localized reduced basis multiscale method for parabolic problems applied to a thermal model of batteries with resolved porous electrodes. Numerical experiments are given that demonstrate the reduction capabilities of the presented approaches for these real world applications

    VOC Air Pollution in Urban Areas – A Microscale Model experimentally validated

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    Previous theoretical and experimental studies (S. T. A.- Università di Pisa (DIMNP), 1998; Agostini E., M. Corezzi, I. Ciucci, M. Mazzini 2003; Agostini E., I. Ciucci, M. Mazzini, S. Strinati, 2003) even if partial, evidenced the problem of atmospheric pollution by Volatile Organic Compounds (VOC) in Livorno (Tuscany). This pollution is caused mainly by the presence of an important refinery, other industries and traffic. Other relevant VOC emission sources are linked to port activities and to numerous small companies using paints and solvents. Figure 1 shows the map of Livorno, situated on the Tyrrhenian sea. This is a simple site from the orography point of view, except for the southern zone where a promontory and a chain of hills impose a more complex pattern of air fluxes. The industrial zone is localized in the north of the map and the harbour activities along the coast (west area). It’s difficult to define a specific zone for the companies using solvents and paints, even though a grater concentration is present around the axis Viale Carducci – Piazza Repubblica – Via Grande. The map outlines also the air pollution measurement stations managed by ARPAT (points) and the meteorological stations (crosses). The simulation of the emission scenario, was done by using ISC3 (U. S. Environmental Protection Agency) code for treating diffuse sources and CALINE4 (California Department of Transportation) for those related to traffic on main roads. The research work focuses the attention on the results of model validation by experimental data obtained along the roads of the studied area. The possibility to extend the application of this model to sites with similar orography and town-planning characteristics is also discussed in the aim of obtaining information about the level of atmospheric pollution on sites where there aren’t measurement stations

    An individual-based model to explore the impacts of lesser-known social dynamics on wolf populations

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    The occurrence of wolf populations in human-dominated landscapes is challenging worldwide because of conflicts with human activities. Modeling is an important tool to project wolf dynamics and expansion, and help in decision making concerning management and conservation. However, some individual behaviors and pack dynamics of the wolf life cycle are still unclear to ecologists. Here we present an individual-based model (IBM) to project wolf populations while exploring the lesser-known processes of the wolf life cycle. IBMs are bottom-up models that simulate the fate of individuals interacting with each other, with population-level properties emerging from the individual-level simulations. IBMs are particularly adapted to represent social species such as the wolf that exhibits complex individual interactions. Our IBM projects wolf demography including fine-scale individual behavior and pack dynamics based on up-to-date scientific literature. We explore four processes of the wolf life cycle whose consequences on population dynamics are still poorly understood: the pack dissolution following the loss of a breeder, the adoption of young dispersers by packs, the establishment of new packs through budding, and the different breeder replacement strategies. While running different versions of the IBM to explore these processes, we also illustrate the modularity and flexibility of our model, an asset to model wolf populations experiencing different ecological and demographic conditions. The different parameterization of pack dissolution, territory establishment by budding, and breeder replacement processes influence the projections of wolf populations. As such, these processes require further field investigation to be better understood. The adoption process has a lesser impact on model projections. Being coded in R to facilitate its understanding, we expect that our model will be used and further adapted by ecologists for their own specific applications

    Histochemical characterisation and gene expression analysis of skeletal muscles from maremmana and aubrac steers reared on grazing and feedlot systems

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    This study aimed to characterise the fibre composition of Triceps brachii (TB) and Semimem-branosus (SM) muscles from 20 Maremmana (MA) and 20 Aubrac (AU) steers, and the effect of grazing activity in comparison with feedlot system. The histochemical method was performed with the m-ATPase method with an acid pre-incubation, thus allowing to distinguish type I, IIA, and IIB fibres. Additionally, on total RNA extracted from SM muscle, the expressions of atp1a1, mt-atp6, and capn1 genes were evaluated, in order to find potential associations with muscle fibre histochemical characteristics. In SM muscle, the MA steers had the greater frequency of oxidative fibres (type I and IIA) and the higher atp1a1 expression, in comparison to AU steers. Conversely, AU steers had a greater frequency of type IIB fibres, and the higher capn1 expression. A similar histochemical pattern was observed in TB muscle. The grazing activity was probably insufficient to determine differences both for fibre proportion and size, and gene expressions, except for mt-atp6 expression that was surprisingly highest in feedlot MA in comparison to other steers. These findings further the knowledge of muscle properties belonging to these breeds, and the effect of voluntary physical activity since few studies were available in this regard

    Spark Plasma Sintering of LiFePO4: AC Field Suppressing Lithium Migration

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    Our work proposes a comparison between Spark Plasma Sintering of LiFePO(4) carried out using an Alternating Current (AC) and Direct Current (DC). It quantifies the Li-ion migration using DC, and it validates such hypothesis using impedance spectroscopy, X-ray photoelectron spectroscopy and inductively coupled plasma optical emission spectroscopy. The use of an AC field seems effective to inhibit undesired Li-ion migration and achieve high ionic conductivity as high as 4.5 × 10(−3) S/cm, which exceeds by one order of magnitude samples processed under a DC field. These results anticipate the possibility of fabricating a high-performance all-solid-state Li-ion battery by preventing undesired Li loss during SPS processing

    Evaluation of microbial contamination of air in two haematology departments equipped with ventilation systems with different filtration devices

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    Background. Nosocomial infections (NI) are above all due to health-care workers practices, but also the contamination of the environment could lead to their rise in health-care facilities. Introduction. In the last years, the incidence of NI has increased due to a substantial rise in the number of immuno-compromised patients. These patients are often gathered in hospital areas declared at ?high risk? of infection such as Hematology and Bone Marrow Transplant ward. In this study, we evaluated microbial contamination of the air in two divisions with high risk patients, focusing on the validity of the air system with correla- tion to the presence or not of the HEPA absolute filters. Methods. An environmental surveillance study has been carried out in two Divisions of Haematology, in two different Hospitals. Investigations have been performed by sampling air and by analyzing bacterial and fungal growth on microbiology plates after an incubation period. Results. Unit A, without HEPA filters in the ventilation systems, showed a gradual increase in the bacterial load 20 and 60 days after cleaning of the ventilation system. Mycetes and Aspergilli were not present in basal conditions, at 20 or 60 days after decontamination. Unit B, equipped with HEPA filters placed at the inlet vents, showed extremely low values of the bacterial load either in basal conditions or upon inspection 60 days after cleaning. No mycetes were present. Discussion. From the results obtained, it was evident that fol- lowing the cleaning operation, the quality of the air is excellent in both types of equipment, since no mycetes were present and the bacterial load was inf. 20 CFU/mc in all the sites tested. However, although in subsequent controls mycetes were absent in both types of equipment, a great difference in the suspended bacterial load was found: Unit B was close to sterility whereas in Unit A a progressive increase was observed

    Frequency Dependent Dynamical Electromechanical Response of Mixed Ionic-Electronic Conductors

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    Frequency dependent dynamic electromechanical response of the mixed ionic-electronic conductor film to a periodic electric bias is analyzed for different electronic and ionic boundary conditions. Dynamic effects of mobile ions concentration (stoichiometry contribution), charge state of acceptors (donors), electron concentration (electron-phonon coupling via the deformation potential) and flexoelectric effect contribution are discussed. A variety of possible nonlinear dynamic electromechanical response of MIEC films including quasi-elliptic curves, asymmetric hysteresis-like loops with pronounced memory window and butterfly-like curves are calculated. The electromechanical response of ionic semiconductor is predicted to be a powerful descriptor of local valence states, band structure and electron-phonon correlations that can be readily measured in the nanoscale volumes and in the presence of strong electronic conductivity.Comment: 36 pages, 10 figures, accepted to J. Appl. Phy

    A modal theorem-preserving translation of a class of three-valued logics of incomplete information

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    International audienceThere are several three-valued logical systems that form a scattered landscape, even if all reasonable connectives in three-valued logics can be derived from a few of them. Most papers on this subject neglect the issue of the relevance of such logics in relation with the intended meaning of the third truth-value. Here, we focus on the case where the third truth-value means unknown, as suggested by Kleene. Under such an understanding, we show that any truth-qualified formula in a large range of three-valued logics can be translated into KD as a modal formula of depth 1, with modalities in front of literals only, while preserving all tautologies and inference rules of the original three-valued logic. This simple information logic is a two-tiered classical propositional logic with simple semantics in terms of epistemic states understood as subsets of classical interpretations. We study in particular the translations of Kleene, Gödel, ᮌukasiewicz and Nelson logics. We show that Priest’s logic of paradox, closely connected to Kleene’s, can also be translated into our modal setting, simply by exchanging the modalities possible and necessary. Our work enables the precise expressive power of three-valued logics to be laid bare for the purpose of uncertainty management
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