Links Between Machining Parameters and Surface Integrity in Drilling Ni-Superalloy

In aerospace industry, the manufacturing of critical parts (high energy components) requires an important validation process to guarantee the quality of the produced parts, and thus their fatigue lifecycle. Globally, this validation consists in freezing the cutting conditions using metallurgical analysis or fatigue trials, and a test on the first article. This process is extremely complex and expensive. In this way establishing the correlation between the cutting conditions and the surface integrity will help us to optimize the manufacture of those parts. In this article, by the means of an experimental method, we define a domain of validation by combining the cutting conditions according to the classic criteria established by AFNOR E66-520 norm (Couple-Tool-Material) and the criteria of surface integrity for the drilling of a Nickel-base superalloy. The experimental device consists in drilling a Ø15.5 mm hole on a 3-axis milling centre instrumented by a 4 components Kistler dynamometer (Fx, Fy, Fz and Mz), a spindle power sensor “Watt-pilote” and three accelerometers placed following the directions X, Y and Z. Scanning Electron Microscopy (SEM) observations, micro-hardness tests and topographic measurements with an optical profilometer, are carried out to characterize the metallurgical state of the holes manufactured. Finally, correlations were respectively made between the cutting conditions, the recorded signals and the metallurgical state of the holes

Identification of influent factors on surface integrity in nickel-base superalloy drilling

For the critical rotating components in aeronautical industry, the metallurgical quality achieved after machining conditions could determine their mechanical behaviour in fatigue. To guarantee this quality, the tools, materials and cutting conditions are frozen during the validation process by a cutup part following by an acceptable surface integrity. Even with the fixed parameters, perturbations can occur during the process and may have a direct impact over the metallurgical quality through the apparition of anomalies, which could reduce the calculated fatigue life. The aim of this study is to define a Process Monitoring technique able to detect the thickness affected by the machining taking into account the flank wear effect

Impact of disturbed drilling conditions on the surface integrity of a Nickel-base superalloy

Manufacturing critical parts for aerospace industry requires an important validation process to guarantee the quality of the produced components, and thus their fatigue life. Even with the best cutting conditions, disturbances can occur during the process and may have a direct impact on metallurgical quality. Through an experimental approach, this work presents the impact, during machining, of a lubricant interruption on the surface integrity and on the Process Monitoring signals. Finally a correlation between the thickness of the thermo-mechanically affected layer and the cutting power is made

Combining NDT tools for analysing the efficiency of repair techniques of wharves: the MAREO project

ISBN: 9780415669863Repair of structures in concrete is still a challenge, especially when access and environment offer a difficult context such as the case of wharves. Concerning the repair of concrete for marine structures, European standards give the requirements in predefined and standardised conditions. However, repair of wharves is performed in harsh conditions such as access, humidity and operator position. These conditions do not enable the direct application of standards. By accounting for these requirements, the repair technique consists in rebuilding the concrete cover and in some cases using protective coating for some beams. In this paper, we focus on the concrete repair techniques. The aim of MAREO project (French project of the National competitive cluster in Civil Engineering and Eco-Building) is to compare several repair techniques carried out in the most complex area for repair: the tidal zone. The project deals with initial performance, sustainability, cost of durability and concrete properties monitoring by Destructive Testing (DT) and Non-Destructive Testing (NDT) techniques. The studied NDT techniques are: impact-echo, surface waves, multi-offset radar, and capacitive method. Both, beams placed in natural exposure and slabs specimens placed in accelerated conditions in laboratory are considered. For all the beams, the contaminated concrete was removed using high-velocity water jets (hydro-demolition). The selected techniques are wet shotcrete, dry shotcrete, formed concrete and manual repair. This paper focuses on the ability of NDT techniques to evaluate the changes of properties related to the chloride ingress in concrete both on site and in accelerated laboratory conditions. The interest of each technique and its sensitivity to several physical factors are highlighted. The need of NDT-combination is illustrated

Managed aquifer recharge in weathered crystalline basement aquifers in India: Monitoring of the effect of tank infiltration on water quality over several monsoon events

International audienceManaged aquifer recharge (MAR) structures like percolation tanks are considered by the Indian national and regional governments as major option for tackling declining groundwater levels due to overexploitation for irrigation purposes (Boisson et al., 2014). Their main purpose is to restore groundwater availability under strong climatic and anthropogenic pressure. Furthermore, MAR-induced dilution with fresh surface water is generally expected to improve groundwater quality with respect to both anthropogenic and geogenic contaminants (total mineralisation, nitrates, chlorides, sulphates and fluoride contents). The impact of a percolation tank on groundwater quality was investigated in a context that is typical for hydro-climatic and geological settings in southern and eastern India: fractured crystalline basement aquifers overlain by a weathering zone under semi-arid climate. Water level data and geochemical indicators (stable isotopes and major ions) were monitored for both groundwater and surface water, over several successive monsoon events. In case of high to very high water levels, the groundwater quality is globally improved. However, in a few cases, the quality of the groundwater can be negatively impacted due to leaching of salts under the tank, particularly during the first rain events of the monsoon. Geogenic fluoride contents in groundwater, induced by water-rock interaction and enhanced by recycling of agricultural return flow under paddy fields, is found to be relatively stable over the year. This finding points out that the underlying processes, mainly dissolution of F-bearing phases like fluorapatites combined with Ca/Na cation exchange and calcite precipitation , both limiting the possibility of F-removal via fluorite precipitation (Pettenati et al., 2013, 2014), are not impacted by the hydrological conditions. This work highlights the complexity of the recharge processes in crystalline aquifers, enhanced by the variability of hydrological conditions. It also provides insights into the possible risk for groundwater quality deterioration in cases of light and short monsoons periods

A New High-Throughput Tool to Screen Mosquito-Borne Viruses in Zika Virus Endemic/Epidemic Areas

International audienceMosquitoes are vectors of arboviruses affecting animal and human health. Arboviruses circulate primarily within an enzootic cycle and recurrent spillovers contribute to the emergence of human-adapted viruses able to initiate an urban cycle involving anthropophilic mosquitoes. The increasing volume of travel and trade offers multiple opportunities for arbovirus introduction in new regions. This scenario has been exemplified recently with the Zika pandemic. To incriminate a mosquito as vector of a pathogen, several criteria are required such as the detection of natural infections in mosquitoes. In this study, we used a high-throughput chip based on the BioMark™ Dynamic arrays system capable of detecting 64 arboviruses in a single experiment. A total of 17,958 mosquitoes collected in Zika-endemic/epidemic countries (Brazil, French Guiana, Guadeloupe, Suriname, Senegal, and Cambodia) were analyzed. Here we show that this new tool can detect endemic and epidemic viruses in different mosquito species in an epidemic context. Thus, this fast and low-cost method can be suggested as a novel epidemiological surveillance tool to identify circulating arboviruses

Intégrer des ressources numériques dans les collections

Cet ouvrage s’inscrit dans la continuité de plusieurs autres volumes de la collection afin de proposer aux bibliothécaires et documentalistes des clés pour aborder et gérer efficacement la documentation dématérialisée : une douzaine d’auteurs s’attachent à présenter les modalités de sélection, d’acquisition, de signalement, d’évaluation et de conservation propres à ces ressources en développant en filigrane un questionnement sur la fonction de la bibliothèque. Prenant appui aussi bien sur des bibliothèques de lecture publique que des universités, le plan s’organise autour de quatre parties pragmatiques et opératoires : connaître le contexte ; sélectionner et acquérir ; intégrer et sélectionner et, enfin, évaluer et conserver

Concevoir la ville à partir des gares, Rapport final du Projet Bahn.Ville 2 sur un urbanisme orienté vers le rail

Expérimenter de nouvelles façons de faire de l'aménagement et du développement urbain autour des gares ? C'est l'objectif du projet franco-allemand Bahn.Ville 2, recherche-action qui vise à promouvoir « un urbanisme orienté vers le rail ». Valoriser les investissements faits sur les lignes ferroviaires régionales périurbaines par des mesures d'accompagnement dans le domaine de l'urbanisme, optimiser les conditions d'accessibilité aux gares de ces lignes, améliorer la qualité du service rendu aux usagers dans les lieux d'échanges autour de ces gare telles sont les ambitions de ce projet réalisé sur la période 2007-2009. Il s'agit de tester les conditions de la mise en œuvre d'un urbanisme orienté vers le rail

Brain Responses to Violet, Blue, and Green Monochromatic Light Exposures in Humans: Prominent Role of Blue Light and the Brainstem

BACKGROUND: Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established. METHODOLOGY/PRINCIPAL FINDINGS: We exposed 15 participants to short duration (50 s) monochromatic violet (430 nm), blue (473 nm), and green (527 nm) light exposures of equal photon flux (10(13)ph/cm(2)/s) while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus. CONCLUSION/SIGNIFICANCE: These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function

Sorption and degradation of tebutam in soil under controlled laboratory conditions

This study investigates tebutam (N-benzyl-N-isopropylpivalamide) sorption and degradation in the surface level (0-20 cm) of a brown silty clay soil. All the experiments were conducted under controlled laboratory conditions using $^{14}$C uniformly ring labelled tebutam. The sorption process was evaluated by adsorption kinetics, adsorption and desorption isotherms using a batch equilibration method. In our conditions, equilibration time for 95% of herbicide adsorbed was 0.21 h. This initial rapid sorption pattern, was followed by slower sorption continuing over 48 h. The adsorption isotherm was well described by the Freundlich equation with K$_{\rm f}$ = 1.48 and n$_{\rm f}$ = 0.95. This corresponds to a K$_{\rm d}$ of 1.48 l$\cdot$kg$^{-1}$ and a K$_{{\rm oc}}$ of 148 l$\cdot$kg$^{-1}$, comparable to the coefficients measured for atrazine. Desorption of tebutam was easy and weakly hysteretic, particularly for large adsorbed amounts. For degradation, data showed that 50% of tebutam was degraded in 14 days (as a percentage of extractable residues), and nearly 41% was mineralized in the same interval. Non-extractable residues reached 46% of initial applied amounts in 12 days. Their slow and gradual release determined after 12 days, appears to supply the mineralization process. Degradation products were formed from the fourth incubation day and three of them appeared to persist in soil media. They reached nearly 80% of extractable residual radioactivity at the end of incubation.Rétention et dégradation du tébutame dans un sol en conditions contrôlées. La rétention et la dégradation du tébutame (N-benzyl-N-isopropylpivalamide) dans le sol, ont été évaluées en conditions de laboratoire à l'aide de la molécule uniformément marquée au $^{14}$C sur le noyau aromatique. Le phénomène de rétention a été apprécié par une cinétique d'adsorption, une isotherme d'adsorption et une isotherme de désorption. Dans les conditions d'étude adoptées, le temps d'équilibre pour observer 95 % de produit adsorbé est de 0,21 h. A cette adsorption rapide fait suite une adsorption lente qui se poursuit au delà de 48 h. L'isotherme d'adsorption est décrite par l'équation de Freundlich avec un coefficient K$_{\rm f}$ de 1,48 et une constante n$_{\rm f}$ de 0,95, ce qui conduit à un coefficient K$_{{\rm oc}}$ de 148 l$\cdot$kg$^{-1}$ comparable à celui de l'atrazine. Enfin, la désorption de l'herbicide est assez facile et le phénomène d'hystérésis est peu marqué, en particulier pour des quantités adsorbées importantes. Concernant la dégradation, les données obtenues ont montré que 50 % du produit appliqué étaient dégradés en 14 jours et que près de 41 % étaient minéralisés dans le même temps. Les résidus non extractibles atteignent 46 % de la dose initialement apportée en 12 jours. Leur teneur diminue à partir de 14 jours. Ces résidus semblent alimenter le processus de minéralisation. Les produits de dégradation sont formés dès le 4e jour et 3 d'entre-eux persistent dans le milieu. Ils atteignent près de 80 % de la radioactivité résiduelle extractible en fin d'incubation