Génération de chemins de couverture pour des opérations automatisées de contrôle non destructif appliquées dans l'industrie aérospatiale

RÉSUMÉ L’industrie aérospatiale accorde un rôle majeur au contrôle non destructif (CND) dans le processus de fabrication et de maintenance des structures et il est utilisé, entre autres, pour détecter des défauts tels que des fissures à un stade précoce. Cependant, les techniques de CND sont encore principalement opérées manuellement, en particulier sur des structures aérospatiales complexes. Plusieurs inconvénients en résultent tels que la pénibilité et le temps d’opération des techniques. De plus, la fiabilité et la répétabilité des résultats d’inspection est susceptible de varier de manière significative puisqu’elles dépendent de l’expérience et de la dextérité de chaque opérateur. Dans le cadre du projet MANU-418 du Consortium de recherche et d’innovation en aérospatiale au Québec (CRIAQ) dans lequel s’inscrit le présent travail de recherche, il a été proposé de développer un système muni d’un bras manipulateur à 6 DDL permettant d’automatiser trois techniques particulières de CND utilisées dans l’industrie aérospatiale : l’inspection par courants de Foucault (ECT), l’inspection par ressuage fluorescent (FPI) et l’inspection par thermographie infrarouge (IRT). L’objectif global du projet MANU-418 est de démontrer que ce système automatisé permet d’obtenir des résultats de détection de défauts (des fissures généralement) en surface et légèrement sous la surface au moins aussi acceptables en termes de fiabilité et de répétabilité que ceux obtenus manuellement. Un des objectifs spécifiques qui découle de ce projet est de développer une méthodologie et un outil logiciel de génération de chemins de couverture adaptés aux trois techniques de CND mentionnées précédemment pour l’inspection de surfaces complexes de structures aérospatiales. Le présent travail de recherche s’attache à la réalisation de cet objectif spécifique. Dans un premier temps, les propriétés de géométrie et de topologie du type de surfaces considérées dans ce projet sont définies (surfaces planes, congés, bords droits, surfaces cylindriques, trou dans la surface). Il est également supposé que le modèle 3D de la surface à inspecter est connu à l’avance. Aussi, l’automatisation de l’inspection ECT étant prioritaire devant celles des techniques FPI et IRT dans le cadre du projet MANU-418, la méthodologie développée se base sur les propriétés de chemin qu’une sonde différentielle à courants de Foucault (appelée ici sonde EC) suit habituellement lors d’une inspection manuelle, tout en permettant de rester utilisable pour les autres techniques. Le chemin d’inspection d’une sonde EC est défini par un balayage en zigzag et cette sonde est généralement en contact léger avec la surface durant le balayage. Aussi, l’axe de la sonde doit en tout temps être normal à la surface et, l’alignement de ses deux bobines doit toujours être orienté le long de sa direction de déplacement. Une première méthodologie est alors proposée pour générer des chemins de couverture sur toute la surface à inspecter en respectant les contraintes de la sonde EC.----------ABSTRACT Non destructive testing (NDT) plays an important role in the aerospace industry during the fabrication and maintenance of the structures built and is used, among other useful applications, to detect flaws such as cracks at an early stage. However, NDT techniques are still mainly done manually, especially on complex aeronautical structures, which then results in several drawbacks. In addition to be difficult and time-consuming, reliability and repeatability of inspection results are likely to be affected, since they rely on each operator’s experience and dexterity. The present thesis is part of a larger project (MANU-418) of the Consortium for Research and Innovation in Aerospace in Québec (CRIAQ). In this project, it has been proposed to develop a system using a 6-DOF manipulator arm to automate three particular NDT techniques often needed in the aerospace industry: eddy current testing (ECT), fluorescent penetrant inspection (FPI), and infrared thermography (IRT). The main objective of the MANU-418 project is to demonstrate the efficiency of the developed system and provide inspection results of surface and near surface flaws (cracks usually) at least as reliably and repeatably as inspection results from a human operator. One specific objective stemming from the main objective of the project is to develop a methodology and a software tool to generate covering paths adapted for the three forementioned NDT techniques to inspect the complex surfaces of aerospace structures. The present thesis aims at reaching this specific objective. At first, geometrical and topological properties of the surfaces considered in this project are defined (flat surfaces, round and straight edges, cylindrical or near cylindrical surfaces, holes). It is also assumed that the 3D model of the surface to inspect is known in advance. Moreover, it has been decided within the framework of the MANU-418 project to give priority to the automation of ECT compared with the other techniques (FPI and IRT). As a result, the methodology developed to generate inspection paths is more closely focused on path constraints relative to the manual operations of ECT using a differential eddy current probe (named here EC probe), but it is developed to be flexible enough to be used with the other techniques as well. Common inspection paths for ECT are usually defined by a sweeping motion using a zigzag pattern with the EC probe in mild contact with the inspected surface. Moreover, the main axis of the probe must keep a normal orientation with the surface, and the alignment of its two coils must always be oriented along the direction of its motion. A first methodology is then proposed to generate covering paths on the whole surface of interest while meeting all EC probe motion constraints. First, the surface is meshed with triangular facets, and then it is subdivided into several patches such that their geometry and topology are simpler than the whole surface

Arrival of Paleo-Indians to the Southern Cone of South America: New Clues from Mitogenomes

With analyses of entire mitogenomes, studies of Native American mitochondrial DNA (mtDNA) variation have entered the final phase of phylogenetic refinement: the dissection of the founding haplogroups into clades that arose in America during and after human arrival and spread. Ages and geographic distributions of these clades could provide novel clues on the colonization processes of the different regions of the double continent. As for the Southern Cone of South America, this approach has recently allowed the identification of two local clades (D1g and D1j) whose age estimates agree with the dating of the earliest archaeological sites in South America, indicating that Paleo-Indians might have reached that region from Beringia in less than 2000 years. In this study, we sequenced 46 mitogenomes belonging to two additional clades, termed B2i2 (former B2l) and C1b13, which were recently identified on the basis of mtDNA control-region data and whose geographical distributions appear to be restricted to Chile and Argentina. We confirm that their mutational motifs most likely arose in the Southern Cone region. However, the age estimate for B2i2 and C1b13 (11–13,000 years) appears to be younger than those of other local clades. The difference could reflect the different evolutionary origins of the distinct South American-specific sub-haplogroups, with some being already present, at different times and locations, at the very front of the expansion wave in South America, and others originating later in situ, when the tribalization process had already begun. A delayed origin of a few thousand years in one of the locally derived populations, possibly in the central part of Chile, would have limited the geographical and ethnic diffusion of B2i2 and explain the present-day occurrence that appears to be mainly confined to the Tehuelche and Araucanian-speaking grou

Liver biopsy results in patients with sickle cell disease on chronic transfusions: Poor correlation with ferritin levels

Background: Chronic transfusions are effective in preventing stroke and other complications of sickle cell disease. The aim of this study was to determine whether serum ferritin levels correlated with liver iron content in sickle cell patients on chronic transfusion. Procedure: Forty-four liver biopsy specimens from 38 patients with homozygous sickle cell anemia (HbSS) and one patient with sickle thalassemia receiving chronic transfusions were studied. Five patients underwent a second liver biopsy for follow up. Three ferritin measurements were used to calculate a mean for each patient. The association between serum ferritin levels and liver iron quantitation was measured using the Spearman rank correlation, and sensitivity and specificity were determined for selected threshold values of serum ferritin. Results: Serum ferritin levels ranged from 515 to 6076 ng/ml, liver iron concentration ranged from 1.8 to 67.97 mg/g dry weight. The amount of iron per gram liver dry weight was moderately correlated with serum ferritin values ( r  = 0.46). The correlation of duration of transfusion with serum ferritin ( r  = 0.40) and with liver iron content ( r  = 0.41) also indicated moderate correlation. Liver biopsy results led to changes in the management after 29/44 (66%) of the biopsies. Serum ferritin ≥2500 ng/ml predicted high liver iron content (≥7 mg/g), with a sensitivity of 62.5% and a specificity of 77.8%. Conclusion: We found a poor correlation between serum ferritin levels and liver iron content (LIC). Despite being on chelation therapy, many patients on chronic transfusion had high levels of liver iron. Measurement of LIC is highly recommended in these patients. Pediatr Blood Cancer 2008;50:62–65. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57399/1/21215_ftp.pd

The structure of the agrochemical fungicidal 4-Chloro-3-(3,5-dichloropheny)-1H-pyrazole, RPA 406194 and related compounds

The difficulties to obtain convenient monocrystals of the important fungicide RPA 406194 have been overcome by a combination of solid state 13C NMR, X-ray powder diffraction and molecular modeling. The compound, a 3-aryl tautomer, crystallizes forming infinite chains of molecules bonded by N–H· · ·N hydrogen bonds, leading to needle-shaped crystals. The tautomerism (equilibrium constant and energy barrier) of this compound in solution has been studied

Importance of optimal dosing ≥30 mg/kg/d during deferasirox treatment: 2.7-yr follow-up from the ESCALATOR study in patients with β-thalassaemia

Following 1-yr deferasirox therapy in the ESCALATOR study, 57% of previously chelated patients with β-thalassaemia achieved treatment success (maintenance of or reduction in liver iron concentration (LIC) vs. baseline LIC). Seventy-eight per cent had dose increases at median of 26 wk, suggesting that 1-yr results may not have reflected full deferasirox efficacy. Extension data are presented here. Deferasirox starting dose was 20 mg/kg/d (increases to 30/40 mg/kg/d permitted in the core/extension, respectively). Efficacy was primarily assessed by absolute change in LIC and serum ferritin. Overall, 231 patients received deferasirox in the extension; 67.4% (P < 0.0001) achieved treatment success. By the end of the extension, 66.2% of patients were receiving doses ≥30 mg/kg/d. By the end of the 1-yr extension, mean LIC had decreased by 6.6 ± 9.4 mg Fe/g dw (baseline 19.6 ± 9.2; P < 0.001) and median serum ferritin by 929 ng/mL (baseline 3356; P < 0.0001). There was a concomitant improvement in liver function markers (P < 0.0001). Fewer drug-related adverse events were reported in extension than core study (23.8% vs. 44.3%). Doses ≥30 mg/kg/d were generally required because of high transfusional iron intake and high baseline serum ferritin levels, highlighting the importance of administering an adequate dose to achieve net negative iron balance

The Paleo-Indian Entry into South America According to Mitogenomes

Recent and compelling archaeological evidence attests to human presence 14.5 ka at multiple sites in South America and a very early exploitation of extreme high-altitude Andean environments. Considering that, according to genetic evidence, human entry into North America from Beringia most likely occurred 16 ka, these archeological findings would imply an extremely rapid spread along the double continent. To shed light on this issue from a genetic perspective, we first completely sequenced 217 novel modern mitogenomes of Native American ancestry from the northwestern area of South America (Ecuador and Peru); we then evaluated them phylogenetically together with other available mitogenomes (430 samples, both modern and ancient) from the same geographic area and, finally, with all closely related mitogenomes from the entire double continent. We detected a large number (N¼ 48) of novel subhaplogroups, often branching into further subclades, belonging to two classes: those that arose in South America early after its peopling and those that instead originated in North or Central America and reached South America with the first settlers. Coalescence age estimates for these subhaplogroups provide time boundaries indicating that early Paleo-Indians probably moved from North America to the area corresponding to modern Ecuador and Peru over the short time frame of 1.5 ka comprised between 16.0 and 14.6 ka

Reproducibility of exhaled nitric oxide in smokers and non-smokers: relevance for longitudinal studies

<p>Abstract</p> <p>Background</p> <p>Currently, there is much interest in measuring fractional exhaled nitric oxide (<b>FE_NO</b>) in populations. We evaluated the reproducibility of <b>FE_NO</b>in healthy subjects and determined the number of subjects necessary to carry out a longitudinal survey of <b>FE_NO</b>in a population containing smokers and non-smokers, based on the assessed reproducibility.</p> <p>Methods</p> <p>The reproducibility of <b>FE_NO</b>was examined in 18 healthy smokers and 21 non-smokers. <b>FE_NO</b>was assessed once at 9 AM on five consecutive days; in the last day this measurement was repeated at 2 PM. Respiratory symptoms and medical history were assessed by questionnaire. The within- and between-session repeatability of <b>FE_NO</b>and log-transformed <b>FE_NO</b>was described. The power of a longitudinal study based on a relative increase in <b>FE_NO</b>was estimated using a bilateral t-test of the log-transformed <b>FE_NO</b>using the between-session variance of the assay.</p> <p>Results</p> <p><b>FE_NO</b>measurements were highly reproducible throughout the study. <b>FE_NO</b>was significantly higher in males than females regardless of smoking status. <b>FE_NO</b>was positively associated with height (p < 0.001), gender (p < 0.034), smoking (p < 0.0001) and percent FEV₁/FVC (p < 0.001) but not with age (p = 0.987). The between-session standard deviation was roughly constant on the log scale. Assuming the between-session standard deviation is equal to its longitudinal equivalent, either 111 or 29 subjects would be necessary to achieve an 80% power in detecting a 3% or a 10% increase in <b>FE_NO</b>respectively.</p> <p>Conclusion</p> <p>The good reproducibility of <b>FE_NO</b>is not influenced by gender or smoking habits. In a well controlled, longitudinal study it should allow detecting even small increases in <b>FE_NO</b>with a reasonable population size.</p

Biomolecular insights into North African-related ancestry, mobility and diet in eleventh-century Al-Andalus.

Funder: Helmholtz Zentrum München – German Research Center for Environmental HealthFunder: Leverhulme TrustHistorical records document medieval immigration from North Africa to Iberia to create Islamic al-Andalus. Here, we present a low-coverage genome of an eleventh century CE man buried in an Islamic necropolis in Segorbe, near Valencia, Spain. Uniparental lineages indicate North African ancestry, but at the autosomal level he displays a mosaic of North African and European-like ancestries, distinct from any present-day population. Altogether, the genome-wide evidence, stable isotope results and the age of the burial indicate that his ancestry was ultimately a result of admixture between recently arrived Amazigh people (Berbers) and the population inhabiting the Peninsula prior to the Islamic conquest. We detect differences between our sample and a previously published group of contemporary individuals from Valencia, exemplifying how detailed, small-scale aDNA studies can illuminate fine-grained regional and temporal differences. His genome demonstrates how ancient DNA studies can capture portraits of past genetic variation that have been erased by later demographic shifts-in this case, most likely the seventeenth century CE expulsion of formerly Islamic communities as tolerance dissipated following the Reconquista by the Catholic kingdoms of the north