Development of a soft sensor for detecting overpitched anodes : detailed investigation of an anode sticking event

Adjusting pitch ratio in green anode formulation is becoming difficult due to the increasing raw material variability. The optimal quantity of pitch yielding the best anode properties for a given aggregate, known as the optimal pitch demand (ODP), changes more frequently and is unknown a priori. Exceeding the OPD increases the risk of generating post-baking anode-sticking events. Previously, the potential of a principal component analysis (PCA)-based monitoring scheme for detecting the onset of these undesirable events was assessed by using a set of five green anode resistivity measurements collected from over 120,000 anodes produced over a two-year period. The squared prediction error (SPE) was shown to be sensitive to abnormal events such as anode sticking. The objective of this paper is to further validate the soft sensor by studying the SPE dynamic behavior during a post-baking sticking event when changes in the anode paste formulation were introduced as part of normal operation. Descriptive and statistical analyses demonstrate that the SPE metric reacts significantly to changes in the recipe. The provided example illustrates how the SPE metric used together with pitch ratio data could help advised the operators of manufacturing conditions posing a higher risk of generating post-baking sticking problems

The EGIM, modular though generic addresses the requirements of the EMSO platforms

The EGIM (EMSO Generic Instrument Module ) is designed to consistently and continuously measure parameters of interest for most major science areas covered by EMSO. This research infrastructure provides accurate records on marine environmental changes from distributed regional nodes around Europe. The system can deliver data that can support the Global Ocean Observing System –Essential Ocean Variables concept, as well as the Marine Strategy Framework Directive towards evaluating environmentalstatus. The EGIM is flexible for adaptation according to site and disciplinespecific requirements. Inter - operability and capacity of future evolution of the system are key aspects of the modularity. The EGIM is able to operate on any EMSO node type: mooring line, sea bed station, cabled or non - cabled and surface buoy to monitor environmental parameters over a wide depth range. Operating modes, power requirements, mechanical design can adapt to the various EMSO node configurations. In addition to sensors already included in the EGIM prototype (temperature, conductivity, pressure, dissolved Oxygen, Turbidity, currents and passive acoustics) the EGIMcan host up to five additional sensors such as chl -a, pCO 2, pH, seismic and photographic/video images ornew sensors. The EGIM provides all the sensor hosting services required ,for instance power distribution, positioning , and protection against bio -fouling . Within EMSO , the EGIM aimsto have a number of ocean locations where the same set of core variables are measured homogeneously: using the same hardware, same sensor references, same qualification methods, same calibration methods, same data format and access and the same maintenance procedures. It’s compact and modular nature allows for flexible deploymentscenarios that include being able to accommodate new instruments such for Essential Ocean Variables and other needs as theirtechnology readiness levels improve.Peer ReviewedPostprint (published version

La Bibliothèque HOA, Bilan et Perspectives

International audienceCet article présente l’état actuel de la bibliothèque HOA en cours de développement, suite à un premier article paru dans les actes des Jim 2012. Nousprésentons en détail l’ensemble des objets. Nous précisons l’apport de la décomposition en ondes planes dans le contexte ambisonique ainsi que l’usage de la synthèse binaurale pour une ambisonie virtuelle. Enfin nous abordons la prise en main de la bibliothèque par les musiciens

An experimental study of the high speed interaction between a labyrinth seal and an abradable coating in a turbo-engine application

A new high-speed test rig was designed to simulate the interactions between labyrinth seals and abradable coatings in similar turbo-engine operating conditions. To determine a solution for turbo-engine efficiency enhancement, we investigated the clearance reduction between the rotary parts in air systems, the successive starts and stops, the thermal expansion and the vibrations that might cause direct rub interactions between a rotary seal, known as a labyrinth seal, and a turbo-engine housing coated with a sacrificial abradable material. High interaction speeds from 0 to 130 m s−1 were obtained using a 5-axis milling machine fitted with a unique magnetic bearings spindle developed specifically for the study. The purpose of this paper is to study the interaction phenomena between an abradable material (Al–Si 6%) and a nickel alloy (Alloy 718) to obtain a first contact assessment under different turbo-engine operating conditions. The experimental results are first presented by visual observations of the posttest samples, as specified by accurate profile measurements. A quantitative approach to the interaction forces recorded during the tests and micrographic observations complete the preliminary study. This work provides new basic data for a preliminary study of the interaction between labyrinth seal teeth tips and abradable coatings in turbo-engine applications

Rumen microbial communities influence metabolic phenotypes in lambs

The rumen microbiota is an essential part of ruminants forging their nutrition and health. Despite its importance, it is not fully understood how various groups of rumen microbes affect host-microbe relationships and functions. The aim of the study was to simultaneously explore the rumen microbiota and the metabolic phenotype of lambs for identifying host-microbe associations and potential biomarkers of digestive functions. Twin lambs, separated in two groups after birth were exposed to practices (isolation and gavage with rumen fluid with protozoa or protozoa-depleted) that differentially restricted the acquisition of microbes. Rumen microbiota, fermentation parameters, digestibility and growth were monitored for up to 31 weeks of age. Microbiota assembled in isolation from other ruminants lacked protozoa and had low bacterial and archaeal diversity whereas digestibility was not affected. Exposure to adult sheep microbiota increased bacterial and archaeal diversity independently of protozoa presence. For archaea, Methanomassiliicoccales displaced Methanosphaera. Notwithstanding, protozoa induced differences in functional traits such as digestibility and significantly shaped bacterial community structure, notably Ruminococcaceae and Lachnospiraceae lower up to 6 folds, Prevotellaceae lower by ~40%, and Clostridiaceae and Veillonellaceae higher up to 10 folds compared to microbiota without protozoa. An orthogonal partial least squares-discriminant analysis of urinary metabolome matched differences in microbiota structure. Discriminant metabolites were mainly involved in amino acids and protein metabolic pathways while a negative interaction was observed between methylotrophic methanogens Methanomassiliicoccales and trimethylamine N-oxide. These results stress the influence of gut microbes on animal phenotype and show the potential of metabolomics for monitoring rumen microbial functions

A Low Power Cryogenic Sapphire Oscillator with better than 10-15 short term frequency stability

International audienceIn the field of Time and Frequency metrology, the most stable frequency source is based on a microwave whispering gallery mode sapphire resonator cooled near 6 K. Provided the resonator environment is sufficiently free of vibration and temperature fluctuation, the Cryogenic Sapphire Oscillator (CSO) presents a short term fractional frequency stability of better than 1 x 10-15. The recent demonstration of a low maintenance CSO based on a pulse-tube cryocooler paves the way for its deployment in real field applications. The main drawback which limits the deployment of the CSO technology is the large electrical consumption (three-phase 8 kW peak / 6 kW stable operation) of the current system. In this paper, we describe an optimized cryostat designed to operate with a low consumption cryocooler requiring only 3 kW single phase of input power to cool down to 4 K a sapphire resonator.We demonstrate that the proposed design is compatible with reaching a state-of-the-art frequency stabilit

The EGIM, EMSO generic instrument module, step towards standardization

Peer ReviewedPostprint (published version

MECSYCO: a Multi-agent DEVS Wrapping Platform for the Co-simulation of Complex Systems

Most modeling and simulation (M&S) questions about complex systems require to take simultaneously account of several points of view. Phenomena evolving at different scales and at different levels of resolution have to be considered. Moreover, expert skills belonging to different scientific fields are needed. The challenges are then to reconcile these heterogeneous points of view, and to integrate each domain tools (formalisms and simulation software) within the rigorous framework of the M&S process. To answer to this issue, we propose here the specifications of the MECSYCO co-simulation middleware. MECSYCO relies on the universality of the DEVS formalism in order to integrate models written in different formalism. This integration is based on a wrapping strategy in order to make models implemented in different simulation software inter-operable. The middleware performs the co-simulation in a parallel, decentralized and distributable fashion thanks to its modular multi-agent architecture. We detail how MECSYCO perform hybrid co-simulations by integrating in a generic way already implemented continuous models thanks to the FMI standard, the DEV&DESS formalism and the QSS method. The DEVS wrapping of FMI that we propose is not restricted to MECSYCO but can be performed in any DEVS-based platform. We show the modularity and the genericity of our approach through an iterative smart heating system M&S. Compared to other works in the literature, our proposition is generic thanks to the strong foundation of DEVS and the unifying features of the FMI standard, while being fully specified from the concepts to their implementations

The wear mechanisms occurring in a labyrinth seal/abradable contact depending on the incursion depth parameter

The contact behavior of an abradable coating (Al-Si 6%) and a labyrinth seal tooth (stainless steel) in a turbo-engine application was studied as a function of the incursion depth parameter, during labyrinth seal/abradable interaction. A controlled and a gradual increase of the labyrinth seal incursion (by step of 50 μm) is performed to obtain the chronological contact evolution under severe operating tribological conditions. The labyrinth seal/abradable contact experiments were conducted on a dedicated test rig able to reach high contact speeds from 0 to 130 m.s−1. To complete contact forces measurement during tests, a suitable instrumentation (acoustic emission sensor, accelerometer, thermocouples, etc.) is developed and coupled as close as possible of the interaction area. The experimental results from the both severe tribological conditions are presented by an analysis of signals recorded during contact tests. Macrographic and micrographic rub-groove observations of post tests samples, coupled with recorded signals from the contact complete the Al-Si 6% behavior study. A wear process description using the third body approach has been proposed to sum up the whole tribological results. Two different varieties of particles production have been identified; a ductile and an adhering layer on the rub-groove bottom and pulverulent fine powder particles, thus providing two different kind of third body and two different material flows