Elastic instability in stratified core annular flow

We study experimentally the interfacial instability between a layer of dilute polymer solution and water flowing in a thin capillary. The use of microfluidic devices allows us to observe and quantify in great detail the features of the flow. At low velocities, the flow takes the form of a straight jet, while at high velocities, steady or advected wavy jets are produced. We demonstrate that the transition between these flow regimes is purely elastic -- it is caused by viscoelasticity of the polymer solution only. The linear stability analysis of the flow in the short-wave approximation captures quantitatively the flow diagram. Surprisingly, unstable flows are observed for strong velocities, whereas convected flows are observed for low velocities. We demonstrate that this instability can be used to measure rheological properties of dilute polymer solutions that are difficult to assess otherwise.Comment: 4 pages, 4 figure

THE EFFECTS OF COUNTERFEIT ON LUXURY BRAND BUYING BEHAVIOR, IN TERMS OF CONSUMPTION EXPERIENCE

A large number of studies on counterfeiting explore consumer behaviors in the consumption of counterfeit articles. But few of them consider luxury brand consumers and counterfeiting. Our research attempts to contribute to this field by studying strategies adopted by luxury brand consumers in the face of counterfeiting (Commuri 2009). To do so, we use the concept of an "experience of another self" in buying a product (Dampérat et al., 2002), which focuses on personal and social objects of consumption.Counterfeit consumption, Luxury brand, Consumption experience

The impact of step-down line extension on consumer-brand relationships: A risky strategy for luxury brands

This paper analyzes the role of the brand concept (luxury vs. non-luxury) in the impact of step-down line extension on consumer-brand relationships. A before-and-after pseudo-experimental study conducted on the Internet among BMW and Peugeot buyers shows that step-down line extension negatively influences the main variables of consumer-brand relationships (e.g., self-brand connections, brand attachment, brand trust and brand commitment) only for the luxury brand BMW. On the contrary, no dilution effects are found for the non-luxury brand Peugeot.vertical line extension, dilution effects; consumer-brand relationships;luxury brands; cars; PSL approach

Formal specification of a self-sustainable holonic system for smart electrical micro-grids

Stand-alone micro-grids have emerged within the smart grids field, facing important challenges related to their proper and efficient operation. An example is the self-sustainability when the micro-grid is disconnected from the main utility, e.g., due to a failure in the main utility or due to geographical situations, which requires the efficient control of energy demand and production. This paper describes the formal specification of a holonic system architecture that is able to perform the automation control functions in electrical stand-alone micro-grids, particularly aiming to improve their self-sustainability. The system aims at optimizing the power flow among the different electrical players, both producers and consumers, to keep the micro-grid operating even under adverse situations. The behaviour of each individual holon and their coordination patterns were modelled, analysed and validated using the Petri net formalism, allowing the complete verification of the system correctness during the design phase.info:eu-repo/semantics/publishedVersio

Quand l'information échappe à ses créateurs : le cas de l'artificialisation des terres agricoles en Languedoc-Roussillon

International audienceThis article aims to describe how the quantification of a phenomenon in relation to a specific worldview spreads and is distorted. This project has been supported by a regional public authority in Languedoc-Roussillon (France), and consisted in the production of information so to quantify and qualify the farmland decrease due to urban sprawl. The paper is based on Latour's actor-network theory; it characterizes the process of enrolment, and the development of dissidences. Identifying contradictory logics and dissidences help questioning the complexity of ‘closing the black-box' regarding information production and of sensemaking between heterogeneous actants involved in a supposed-to-be public debate.Cet article vise à spécifier comment la quantification d'un phénomène fondée sur une certaine vision du monde se propage et se déforme. Ce projet a été porté par une direction déconcentrée de l'Etat soucieuse de l'emprise croissante du bâti sur les terres agricoles en Languedoc-Roussillon. Le cadre théorique mobilisé, la sociologie de la traduction, permet d'identifier les grandes étapes d'intéressement, d'enrôlement, ainsi que le développement de controverses. Les difficultés rencontrées interrogent sur la complexité de clôture de processus innovants s'agissant de production d'information et de co-construction de sens associant des actants hétérogènes impliqués dans des procédures de débat public

On the variability of the slow solar wind: New insights from the modelling and PSP-WISPR observations

We analyse the signature and origin of transient structures embedded in the slow solar wind, and observed by the Wide-Field Imager for Parker Solar Probe (WISPR) during its first 10 passages close to the Sun. WISPR provides a new in-depth vision on these structures, which have long been speculated to be a remnant of the pinch-off magnetic reconnection occurring at the tip of helmet streamers. We pursue the previous modelling works of Reville (2020b, 2022) that simulate the dynamic release of quasi-periodic density structures into the slow wind through a tearing-induced magnetic reconnection at the tip of helmet streamers. Synthetic WISPR white-light (WL) images are produced using a newly developed advanced forward modelling algorithm, that includes an adaptive grid refinement to resolve the smallest transient structures in the simulations. We analyse the aspect and properties of the simulated WL signatures in several case studies, typical of solar minimum and near-maximum configurations. Quasi-periodic density structures associated with small-scale magnetic flux ropes are formed by tearing-induced magnetic reconnection at the heliospheric current sheet and within 3-7Rs. Their appearance in WL images is greatly affected by the shape of the streamer belt and the presence of pseudo-streamers. The simulations show periodicities on the ~90-180min, ~7-10hr and ~25-50hr timescales, which are compatible with WISPR and past observations. This work shows strong evidence for a tearing-induced magnetic reconnection contributing to the long-observed high variability of the slow solar wind.Comment: 23 pages, 14 figures, to appear in Astronomy & Astrophysics, associated movies available at https://doi.org/10.5281/zenodo.813559

L'appréciation de la fécondité des taureaux à l'insémination artificielle : étude sur quelques problèmes relatifs à la mesure des facteurs de diffusion du sperme par méthode biologique

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