Planetary bearing defect detection in a commercial helicopter main gearbox with vibration and acoustic emission

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Helicopter gearboxes significantly differ from other transmission types and exhibit unique behaviors that reduce the effectiveness of traditional fault diagnostics methods. In addition, due to lack of redundancy, helicopter transmission failure can lead to catastrophic accidents. Bearing faults in helicopter gearboxes are difficult to discriminate due to the low signal to noise ratio (SNR) in the presence of gear vibration. In addition, the vibration response from the planet gear bearings must be transmitted via a time-varying path through the ring gear to externally mounted accelerometers, which cause yet further bearing vibration signal suppression. This research programme has resulted in the successful proof of concept of a broadband wireless transmission sensor that incorporates power scavenging whilst operating within a helicopter gearbox. In addition, this paper investigates the application of signal separation techniques in detection of bearing faults within the epicyclic module of a large helicopter (CS-29) main gearbox using vibration and Acoustic Emissions (AE). It compares their effectiveness for various operating conditions. Three signal processing techniques including an adaptive filter, spectral kurtosis and envelope analysis, were combined for this investigation. In addition, this research discusses the feasibility of using AE for helicopter gearbox monitoring

Identification et variabilité des circulations de brises dans les régions viticoles de la bordure helvétique sud-ouest du lac Léman.

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Projection climatiques régionales et services climatiques associés dans le bassin sud-ouest de l'océan Indien

International audienceIn the former Cordex program, regional climate models were run over Africa and only covered the western part of the South Indian Ocean at a coarse 50-km resolution while a 12-km resolution was used for Europe. A 50-km resolution is insufficient for island territories as small and steep as those in the Indian Ocean. Yet this area is especially vulnerable to natural catastrophes related to the effects of climate change: it is the third region in the world most affected by extreme climatic events. The need for climate services over that populated area has now become a critical issue. Both dynamical and statistical downscaling from a few ongoing CMIP6 simulations were therefore used to obtain regional climate information on a large area of the southwest Indian Ocean that includes most of the inhabited countries from the coasts of Mozambique (33°E) to 74°E as well as the main area of tropical cyclone genesis [2-28°S]. The limited area model ALADIN was implemented in its climate version at 12-km resolution and the first runs were coupled by outputs from one of the CMIP6 Earth Simulation Coupled Models named CNRM-ESM2-1. We will present the numerical and statistical tools used for this regional climate study as well as the first projections obtained for ssp126 (RCP2.6), ssp245 (RCP4,5) and ssp585 (RCP8.5) scenarios over the 2015-2100 period. Results will be illustrated for the southwest Indian ocean basin as well as for the main islands of the IOC member countries: Madagascar, Reunion, Mauritius, Seychelles, and Comoros where observations over the 1981-2010 period were used for model bias correction using the quantile-quantile matching method. For climate uncertainty representativeness, the 2015-2100 evolution of both ALADIN and CNRM-ESM2-1 temperature and precipitation averages over our region will be compared to that of the other available CMIP6 simulations. This work is part of the BRIO (Building Resilience in the Indian Ocean) project which aims at supporting the Indian Ocean Commission (IOC) member countries in the implementation of their adaptation policies with respect to climate change (regarding water resources, health and other issues). This project will provide a set of high quality climate-related data on a free-access online regional portal as well as climate services. It is funded by the Agence Française de Développement (AFD), through the Adapt’Action Facility, in cooperation with the IOC

Evaluation of a mesoscale dispersion modelling tool during the CAPITOUL experiment

Atmospheric transport and dispersion were investigated during the CAPITOUL campaign using measurements of sulphur hexafluoride (SF6) tracer. Six releases of SF6 tracer were performed (March 9-11 and July 1-3, 2004) in the same suburban area of Toulouse conurbation, during the Intensive Observing Periods (IOP) of CAPITOUL. Concentration data were collected both at ground-level along axes perpendicular to the wind direction (at distances ranging between 280 m and 5000 m from the release point), and above the ground at 100 m and 200 m height using aircraft flights. Meteorological conditions were all associated with daytime anticyclonic conditions with weak winds and convective clear and cloudy boundary layers. A meso-scale dispersion modelling system, PERLE, developed at Meteo-France for environmental emergencies in case of atmospheric accidental release, was evaluated in terms of meteorology and dispersion, for the different tracer experiments, in its operational configuration. PERLE is based on the combination of the non-hydrostatic meso-scale MESO-NH model, running at 2 km horizontal resolution, and the Lagrangian particle model SPRAY. The statistical meteorological evaluation includes two sets of simulations with initialisation from ECMWF or ALADIN. The meteorological day-to-day error statistics show fairly good Meso-NH predictions, in terms of wind speed, wind direction and near-surface temperature. A strong sensitivity to initial fields concerns the surface fluxes, crucial for dispersion, with an excessive drying of the convective boundary layer with ALADIN initial fields, leading to an overprediction of surface sensible heat fluxes. A parameterization of dry and shallow convection according to the Eddy-Diffusivity-Mass-Flux (EDMF) approach (Pergaud et al. 2008) allows an efficient mixing in the Convective Boundary Layer (CBL) and improves significantly the wind fields. A statistical evaluation of the dispersion prediction was then performed and shows a realistic behaviour of the system, with a good location of the concentration maxima. But the lateral spread of the plumes is quasi-systematically underestimated, mainly in July, even when meteorological conditions are well reproduced. In the same way, higher integrated concentration values are slightly overestimated. The remove of the EDMF scheme in Meso-NH artificially improves the horizontal dispersion, underlying compensating errors. Sensitivity tests performed on the Lagrangian time scales in the coupling Meso-NH-SPRAY have been conducted. But they don't solve the shortcoming and lead to the conclusion that SPRAY could have some difficulties to correctly reproduce the mixing for daytime thermal convection. © Springer-Verlag 2008

Variability of grapevine phenology in Swiss vineyards bordering the Geneva Lake : influence of temperature and local atmospheric circulation.

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Seamless chronostratigraphic solid geology of the North Australian Craton

Geological maps are one of the most important datasets used in resource exploration and management. Despite increasing demand for subsurface resources such as minerals, groundwater and energy, maps of the inferred subsurface geology of Australia and other continents have been limited to small regions or jurisdictions. Here, we present the first seamless semi-continental chronostratigraphic solid geology dataset of the North Australian Craton. This dataset comprises five time slices of stratigraphic units: Cenozoic, Mesozoic, Paleozoic, Neoproterozoic and pre-Neoproterozoic. Interpretation of covered units is based on available data: surface geology and solid geology maps, magnetic intensity and gravity images, drilling logs, reflection seismic profiles and airborne electromagnetic soundings. In total, 2008 units have been mapped, all linked to the Australian Stratigraphic Units Database. So far, these maps have led to a refinement of sedimentary basin and tectonic province outlines, lessened the risks of mineral exploration through Australia’s extensive superficial cover, disclosed geological units known to host resources elsewhere, and highlighted undercover regions with poor geological constraints

Development of advanced weather and climate modelling tools to help vineyard regions adapt to climate change

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Australian continental-scale multilayered chronostratigraphic interpretation of airborne electromagnetics

<p>A key issue for explorers in Australia is the abundant sedimentary and regolith cover obscuring access to underlying potentially prospective rocks. Multilayered chronostratigraphic interpretation of regional broad line- spaced (~20 km) airborne electromagnetic (AEM) conductivity sections have led to breakthroughs in Australia's near-surface geoscience. A dedicated/systematic workflow has been developed to characterise the thickness of cover and the depth to basement rocks, by delineating contact geometries, and by capturing stratigraphic units, their ages and relationships. Results provide a fundamental geological framework, currently covering 27% of the Australian continent, or approximately 2,085,000 km 2. Delivery as precompetitive data in various non-proprietary formats and on various platforms ensures that these interpretations represent an enduring and meaningful contribution to academia, government and industry. The outputs support resource exploration, hazard mapping, environmental management, and uncertainty attribution. This work encourages exploration investment, can reduce exploration risks and costs, helps expand search area whilst aiding target identification, and allows users to make well-informed decisions. Presented herein are some key findings from interpretations in potentially prospective, yet in some cases, underexplored regions from around Australia.</p>Open-Access Online Publication: November 3, 202