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

Experience with low-cost telemedicine in three different settings. Recommendations based on a proposed framework for network performance evaluation

BACKGROUND: Telemedicine has been used for many years to support doctors in the developing world. Several networks provide services in different settings and in different ways. However, to draw conclusions about which telemedicine networks are successful requires a method of evaluating them. No general consensus or validated framework exists for this purpose. OBJECTIVE: To define a basic method of performance measurement that can be used to improve and compare teleconsultation networks; to employ the proposed framework in an evaluation of three existing networks; to make recommendations about the future implementation and follow-up of such networks. METHODS: Analysis based on the experience of three telemedicine networks (in operation for 7-10 years) that provide services to doctors in low-resource settings and which employ the same basic design. FINDINGS: Although there are many possible indicators and metrics that might be relevant, five measures for each of the three user groups appear to be sufficient for the proposed framework. In addition, from the societal perspective, information about clinical- and cost-effectiveness is also required. The proposed performance measurement framework was applied to three mature telemedicine networks. Despite their differences in terms of activity, size and objectives, their performance in certain respects is very similar. For example, the time to first reply from an expert is about 24 hours for each network. Although all three networks had systems in place to collect data from the user perspective, none of them collected information about the coordinator's time required or about ease of system usage. They had only limited information about quality and cost. CONCLUSION: Measuring the performance of a telemedicine network is essential in understanding whether the network is working as intended and what effect it is having. Based on long-term field experience, the suggested framework is a practical tool that will permit organisations to assess the performance of their own networks and to improve them by comparison with others. All telemedicine systems should provide information about setup and running costs because cost-effectiveness is crucial for sustainability

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

International audienc

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

Multi-model ensemble analysis of the ETEX-2 experiment

In this paper we investigate the results of multi-model simulations performed on the ETEX-2 experiment by the ENSEMBLE modelling community. New sets of results were created by taking different percentiles of the distribution of the models¿ predicted values. Both single models and the new constructed sets of results have been compared with the observed data. While a similar comparison for the ETEX-1 case indicated the median model was superior to any single model, for the ETEX-2 case, the situation is more complex and no absolute and clear conclusions can be obtained. However, for emergency response purposes the median model still can be considered as a useful compromise also for complicated situation such is the ETEX-2 experiment. Keywords: multi-model ensemble, percentile models.JRC.H.4-Transport and air qualit