Evaluation of process causes and influences of residual stress on gear distortion

In the automotive industry, heat treatment of components is implicitly related to distortion. This phenomenon is particularly obvious in the case of gears because of their typical and precise geometry. Even if distortion can be anticipated to an extent by experience, it remains complex to comprehend. This paper presents an approach to estimate the distortion based on the idea of a distortion potential taking into account not only geometry but also the manufacturing process history. Then the idea is developed through simulation and experiments including annealing to understand the impact of residual stress on gear distortion in an industrial case study

Evaluation of process causes and influences of residual stress on gear distortion

In the automotive industry, heat treatment of components is implicitly related to distortion. This phenomenon is particularly obvious in the case of gears because of their typical and precise geometry. Even if distortion can be anticipated to an extent by experience, it remains complex to comprehend. This paper presents an approach to estimate the distortion based on the idea of a distortion potential taking into account not only geometry but also the manufacturing process history. Then the idea is developed through simulation and experiments including annealing to understand the impact of residual stress on gear distortion in an industrial case study

Modélisation EM haute fréquence d'arbre pour l'imagerie SAR haute résolution

International audienceDans ce travail, nous nous intéressonsà l'élaboration d'un modèleélectromagnétique d'arbre réaliste, adaptéà l'imagerie radar haute fréquence et haute résolution. Cette premièreétape viseàétablir une modélisation de référence qui permettra dans un second temps l'élaboration d'un modèle approché exploitable pour des scènes de grandes dimensions. Ce premier modèle est réalisé en deux temps. Tout d'abord, la réalisation d'une représentation 3D est faiteà partir de logiciels de modélisation graphique. Ensuite, le maillage généré est exploité pour calculer la visibilité ainsi que la réflectivité des différents contributeurs du signal radar

Metabolic Syndrome and Early-Onset Coronary Artery Disease Is the Whole Greater Than Its Parts?

ObjectivesWe sought to examine the association between the metabolic syndrome (MetS) (defined both by the 2001 National Cholesterol Educational Program Adult Treatment Panel III [ATP-III] definition and the American Heart Association/National Heart, Lung and Blood Institute [AHA/NHLBI] revision incorporating the lower threshold for impaired fasting glucose [IFG]) and early-onset coronary artery disease (CAD).BackgroundThe impact of MetS on premature CAD has not been studied extensively. Lowering the threshold to define the IFG component (from 110 to 100 mg/dl) and the value of the syndrome as a whole versus its individual components are subjects of intense debate.MethodsWe performed a case-control study with 393 early-onset CAD subjects (acute myocardial infarction, angina with ≥50% stenosis, or coronary revascularization) in men under age 46 years or women under age 56 years and 393 control subjects individually matched for gender, age, and race/ethnicity.ResultsBy conditional logistic regression, presence of ATP-III MetS without diabetes (adjusted odds ratio [adj-OR] 4.9; 95% confidence interval [CI] 3.4 to 8.0) and with diabetes (adj-OR 8.0, 95% CI 4.39 to 14.6) was a strong independent determinant of early-onset CAD. Using the AHA/NHLBI revision, these ORs became slightly stronger. However, neither definition of MetS remained significantly associated with early-onset CAD in multivariate models adjusting for individual components.ConclusionsThe presence of MetS imparts a high risk of early-onset clinical CAD, but the prognostic information associated with the syndrome is not greater than the sum of its parts

Biochar-based fertilizer: Supercharging root membrane potential and biomass yield of rice

Biochar-based compound fertilizers (BCF) and amendments have proven to enhance crop yields and modify soil properties (pH, nutrients, organic matter, structure etc.) and are now in commercial production in China. While there is a good understanding of the changes in soil properties following biochar addition, the interactions within the rhizosphere remain largely unstudied, with benefits to yield observed beyond the changes in soil properties alone. We investigated the rhizosphere interactions following the addition of an activated wheat straw BCF at an application rates of 0.25% (g·g−1 soil), which could potentially explain the increase of plant biomass (by 67%), herbage N (by 40%) and P (by 46%) uptake in the rice plants grown in the BCF-treated soil, compared to the rice plants grown in the soil with conventional fertilizer alone. Examination of the roots revealed that micron and submicron-sized biochar were embedded in the plaque layer. BCF increased soil Eh by 85 mV and increased the potential difference between the rhizosphere soil and the root membrane by 65 mV. This increased potential difference lowered the free energy required for root nutrient accumulation, potentially explaining greater plant nutrient content and biomass. We also demonstrate an increased abundance of plant-growth promoting bacteria and fungi in the rhizosphere. We suggest that the redox properties of the biochar cause major changes in electron status of rhizosphere soils that drive the observed agronomic benefits

Climate change, climatic variation and extreme biological responses

Extreme climatic events could be major drivers of biodiversity change, but it is unclear whether extreme biological changes are (i) individualistic (species- or group-specific), (ii) commonly associated with unusual climatic events and/or (iii) important determinants of long-term population trends. Using population time series for 238 widespread species (207 Lepidoptera and 31 birds) in England since 1968, we found that population 'crashes' (outliers in terms of species' year-to-year population changes) were 46% more frequent than population 'explosions'. (i) Every year, at least three species experienced extreme changes in population size, and in 41 of the 44 years considered, some species experienced population crashes while others simultaneously experienced population explosions. This suggests that, even within the same broad taxonomic groups, species are exhibiting individualistic dynamics, most probably driven by their responses to different, short-term events associated with climatic variability. (ii) Six out of 44 years showed a significant excess of species experiencing extreme population changes (5 years for Lepidoptera, 1 for birds). These 'consensus years' were associated with climatically extreme years, consistent with a link between extreme population responses and climatic variability, although not all climatically extreme years generated excess numbers of extreme population responses. (iii) Links between extreme population changes and long-term population trends were absent in Lepidoptera and modest (but significant) in birds. We conclude that extreme biological responses are individualistic, in the sense that the extreme population changes of most species are taking place in different years, and that long-term trends of widespread species have not, to date, been dominated by these extreme changes.This article is part of the themed issue 'Behavioural, ecological and evolutionary responses to extreme climatic events'

Anticipated climate and land-cover changes reveal refuge areas for Borneo's orang-utans

Habitat loss and climate change pose a double jeopardy for many threatened taxa, making the identification of optimal habitat for the future a conservation priority. Using a case study of the endangered Bornean orang-utan, we identify environmental refuges by integrating bioclimatic models with projected deforestation and oil-palm agriculture suitability from the 1950s to 2080s. We coupled a maximum entropy algorithm with information on habitat needs to predict suitable habitat for the present day and 1950s. We then projected to the 2020s, 2050s and 2080s in models incorporating only land-cover change, climate change or both processes combined. For future climate, we incorporated projections from four model and emission scenario combinations. For future land cover, we developed spatial deforestation predictions from 10 years of satellite data. Refuges were delineated as suitable forested habitats identified by all models that were also unsuitable for oil palm – a major threat to tropical biodiversity. Our analyses indicate that in 2010 up to 260 000 km2 of Borneo was suitable habitat within the core orang-utan range; an 18–24% reduction since the 1950s. Land-cover models predicted further decline of 15–30% by the 2080s. Although habitat extent under future climate conditions varied among projections, there was majority consensus, particularly in northeastern and western regions. Across projections habitat loss due to climate change alone averaged 63% by 2080, but 74% when also considering land-cover change. Refuge areas amounted to 2000–42 000 km2 depending on thresholds used, with 900–17 000 km2 outside the current species range. We demonstrate that efforts to halt deforestation could mediate some orang-utan habitat loss, but further decline of the most suitable areas is to be expected given projected changes to climate. Protected refuge areas could therefore become increasingly important for ongoing translocation efforts. We present an approach to help identify such areas for highly threatened species given environmental changes expected this century

Estimation of ash injection in the atmosphere by basaltic volcanic plumes: the case of the Eyjafjallajökull 2010 eruption

During explosive eruptions, volcanic plumes inject ash into the atmosphere and may severely affect air traffic, as illustrated by the 2010 Eyjafjallajökull eruption. Quantitative estimates of ash injection can be deduced from the height reached by the volcanic plume on the basis of scaling laws inferred from models of powerful Plinian plumes. In less explosive basaltic eruptions, there is a partitioning of the magma influx between the atmospheric plume and an effusive lava flow on the ground. We link the height reached by the volcanic plume with the rate of ash injection in the atmosphere via a refined plume model that (1) includes a recently developed variable entrainment law and (2) accounts for mass partitioning between ground flow and plume. We compute the time evolution of the rate of injection of ash into the atmosphere for the Eyjafjallajökull eruption on the basis of satellite thermal images and plume heights and use the dispersion model of the Volcanic Ash Advisory Center of Toulouse to translate these numbers into hazard maps. The classical Plinian model would have overestimated ash injection by about 20% relative to the refined estimate, which does not jeopardize risk assessment. This small error was linked to effective fragmentation by intense interactions of magma with water derived from melting of ice and hence strong mass partitioning into the plume. For a less well fragmented basaltic dry eruption, the error may reach 1 order of magnitude and hence undermine the prediction of ash dispersion, which demonstrates the need to monitor both plume heights and ground flows during an explosive eruption