On-line quality control in polymer processing using hyperspectral imaging

L’industrie du plastique se tourne de plus en plus vers les matériaux composites afin d’économiser de la matière et/ou d’utiliser des matières premières à moindres coûts, tout en conservant de bonnes propriétés. L’impressionnante adaptabilité des matériaux composites provient du fait que le manufacturier peut modifier le choix des matériaux utilisés, la proportion selon laquelle ils sont mélangés, ainsi que la méthode de mise en œuvre utilisée. La principale difficulté associée au développement de ces matériaux est l’hétérogénéité de composition ou de structure, qui entraîne généralement des défaillances mécaniques. La qualité des prototypes est normalement mesurée en laboratoire, à partir de tests destructifs et de méthodes nécessitant la préparation des échantillons. La mesure en-ligne de la qualité permettrait une rétroaction quasi-immédiate sur les conditions d’opération des équipements, en plus d’être directement utilisable pour le contrôle de la qualité dans une situation de production industrielle. L’objectif de la recherche proposée consiste à développer un outil de contrôle de qualité pour la qualité des matériaux plastiques de tout genre. Quelques sondes de type proche infrarouge ou ultrasons existent présentement pour la mesure de la composition en-ligne, mais celles-ci ne fournissent qu’une valeur ponctuelle à chaque acquisition. Ce type de méthode est donc mal adapté pour identifier la distribution des caractéristiques de surface de la pièce (i.e. homogénéité, orientation, dispersion). Afin d’atteindre cet objectif, un système d’imagerie hyperspectrale est proposé. À l’aide de cet appareil, il est possible de balayer la surface de la pièce et d’obtenir une image hyperspectrale, c’est-à-dire une image formée de l’intensité lumineuse à des centaines de longueurs d’onde et ce, pour chaque pixel de l’image. L’application de méthodes chimiométriques permettent ensuite d’extraire les caractéristiques spatiales et spectrales de l’échantillon présentes dans ces images. Finalement, les méthodes de régression multivariée permettent d’établir un modèle liant les caractéristiques identifiées aux propriétés de la pièce. La construction d’un modèle mathématique forme donc l’outil d’analyse en-ligne de la qualité des pièces qui peut également prédire et optimiser les conditions de fabrication.The use of plastic composite materials has been increasing in recent years in order to reduce the amount of material used and/or use more economic materials, all of which without compromising the properties. The impressive adaptability of these composite materials comes from the fact that the manufacturer can choose the raw materials, the proportion in which they are blended as well as the processing conditions. However, these materials tend to suffer from heterogeneous compositions and structures, which lead to mechanical weaknesses. Product quality is generally measured in the laboratory, using destructive tests often requiring extensive sample preparation. On-line quality control would allow near-immediate feedback on the operating conditions and may be transferrable to an industrial production context. The proposed research consists of developing an on-line quality control tool adaptable to plastic materials of all types. A number of infrared and ultrasound probes presently exist for on-line composition estimation, but only provide single-point values at each acquisition. These methods are therefore less adapted for identifying the spatial distribution of a sample’s surface characteristics (e.g. homogeneity, orientation, dispersion). In order to achieve this objective, a hyperspectral imaging system is proposed. Using this tool, it is possible to scan the surface of a sample and obtain a hyperspectral image, that is to say an image in which each pixel captures the light intensity at hundreds of wavelengths. Chemometrics methods can then be applied to this image in order to extract the relevant spatial and spectral features. Finally, multivariate regression methods are used to build a model between these features and the properties of the sample. This mathematical model forms the backbone of an on-line quality assessment tool used to predict and optimize the operating conditions under which the samples are processed

Injection de mousses composites bois/plastiques d'origine post-consommation

Dans cette étude, des matériaux composites bois/plastiques moussés ont été produits par une méthode de moulage par injection. En particulier, les composites sont constitués de fibres de bois et d'une matrice de polyoléfines recyclées (mélange de HDPE et PP). La décomposition thermique de l'azodicarbonamide (ACA), un agent gonflant chimique, fournit le gaz nécessaire à la formation de la mousse microcellulaire. Afin d'étudier ces composites, nous avons varié la concentration de bois, la température du moule ainsi que la teneur en agent gonflant. La caractérisation microscopique des échantillons comprend l'analyse de la structure cellulaire, de l'épaisseur de peau ainsi que de la morphologie des fibres. Les résultats montrent que la température du moule et la teneur en agent gonflant ont très peu d'influence sur la morphologie cellulaire à l'intérieur de la plage de valeurs étudiées. Par ailleurs, l'augmentation de la teneur en fibres augmente le diamètre cellulaire à cause de la nature de l'interface bois/plastiques. Enfin, les tests mécaniques en flexion, torsion, impact et traction ont pour but de caractériser l'effet du bois et du moussage sur ces matériaux tout en liant les propriétés mécaniques aux analyses microscopiques. On observe que les propriétés des échantillons sont supérieures en présence de fibres de bois mais légèrement inférieures lorsque moussés

Optimization of a landfill gas collection shutdown based on an adapted first-order decay model

Abstract: LandGEM’s equation was reformulated to include two types of refuse, fast decaying refuse (FDR) and slow decaying refuse (SDR), whose fractions and key modeling parameters k and L0 were optimized independently for three periods in the life of the Montreal-CESM landfill. Three scenarios were analyzed and compared to actual biogas collection data: (1) Two-Variable Scenario, where k and L0 were optimized for a single type of refuse; (2) Six-Variable Scenario, where three sets of k and L0 were optimized for the three periods and for a single type of refuse; and (3) Seven-Variable Scenario, whereby optimization was performed for two sets of k and L0, one associated with FDR and the second with SDR, and for the fraction of FDR during each of the three periods. Results showed that the lowest error from the error minimization technique was obtained with the Six-Variable Scenario. However, this scenario’s estimation of gas generation was found to be rather unlikely. The Seven-Variable Scenario, which allowed for considerations about changes in landfilling trends, offered a more reliable prediction tool for landfill gas generation and optimal shutdown time of the biogas collection system, when the minimum technological threshold would be attained. The methodology could potentially be applied mutatis mutandis to other landfills, by considering their specific waste disposal and gas collection histories

Acute changes in peritoneal morphology and transport properties with infectious peritonitis and mechanical injury

Acute changes in peritoneal morphology and transport properties with infectious peritonitis and mechanical injury. Peritoneal clearance studies were performed in rats undergoing acute peritoneal dialysis. Some of these animals were then exposed to laparotomy and mechanical drying of the peritoneum. Peritoneal clearance studies were repeated at intervals up to 11 days. Another group of rats was placed on daily peritoneal dialysis and allowed to spontaneously develop peritonitis which was not treated. These rats underwent peritoneal transport studies at differing durations of infection. In all groups, animals were sacrificed at the time of the last transport studies for morphological assessment of the peritoneum by light microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed similar decreases in drainage volume and increases in glucose absorption and protein losses with both infection and drying. Both types of injury resulted in extensive mesothelial structural changes. While drying caused mainly denudation of the mesothelial surface, infectious peritonitis was associated with separation of mesothelial cells, and the appearance of numerous white blood cells between and on mesothelial cells. Exposure to peritoneal dialysis alone had no obvious effects on anatomy. Although changes in the peritoneal microcirculation and deeper structures cannot be excluded as contributing to peritoneal transport alterations, the findings suggest that alterations of mesothelium might explain some of the changes in peritoneal transport properties under the conditions of these studies.Modifications aiguës de la morphologie et des propriétés de transport du péritoine par péritonite infectieuse et lésion mécanique. Des études de clearance péritonéale ont été entreprises chez des rats en dialyse péritonéale aiguë. Certains de ces animaux étaient soumis à une laparotomie et à un séchage mécanique du péritoine. Les études de clearance péritonéale étaient répétées à des intervalles allant jusqu'à 11 jours. Un autre groupe de rat était placé en dialyse péritonéale journalière, et il pouvait développer spontanément une péritonite qui n'était pas traitée. Chez ces rats ont été effectuées des études de transport péritonéal à différents stades d'infection. Dans tous les groupes, les animaux étaient sacrifiés lors de la dernière étude de transport afin d'étudier morphologiquement le péritoine par microscopie optique, microscopie électronique à balayage, et microscopie électronique par transmission. Les résultats ont montré des diminutions du volume de drainage et des augmentations de l'absorption du glucose et des pertes protéiques identiques avec l'infection ou le séchage. Les deux types de lésions ont entrainé des modifications structurelles mésothéliales importantes. Tandis que le séchage entrainait principalement une dénudation de la surface mésothéliale, la péritonite infectieuse était associée à une séparation des cellules mésothéliales, et à l'apparition de nombreux globules blancs entre et sur les cellules mésothéliales. L'exposition à la dialyse péritonéale seule n'avait pas d'effets anatomiques évidents. Bien que la contribution aux altérations du transport péritonéal de modifications de la micro-circulation péritonéale et des structures plus profondes ne puisse être exclue, ces résultats suggèrent que les altérations du mésothélium pourraient expliquer certaines des modifications des propriétés de transport péritonéal dans les conditions de ces études

A ‘spoon full of sugar’ helps the medicine go down: how a participant friendly version of a psychophysics task significantly improves task engagement, performance and data quality in a typical adult sample

Few would argue that the unique insights brought by studying the typical and atypical development of psychological processes are essential to building a comprehensive understanding of the brain. Often, however, the associated challenges of working with non-standard adult populations results in the more complex psychophysical paradigms being rejected as too complex. Recently we created a child (and clinical group) friendly implementation of one such technique – the reverse correlation Bubbles approach and noted an associated performance boost in adult participants. Here, we compare the administration of three different versions of this participant-friendly task in the same adult participants to empirically confirm that introducing elements in the experiment with the sole purpose of improving the participant experience, not only boost the participant’s engagement and motivation for the task but results in significantly improved objective task performance and stronger statistical results

Wafer-scale detachable monocrystalline Germanium nanomembranes for the growth of III-V materials and substrate reuse

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weight reduction, limitation of waste, and cost effectiveness. Herein, we introduce the Porous germanium Efficient Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of wafer-scale detachable monocrystalline Ge NMs on porous Ge (PGe) and substrate reuse. We demonstrate monocrystalline Ge NMs with surface roughness below 1 nm on top of nanoengineered void layer enabling layer detachment. Furthermore, these Ge NMs exhibit compatibility with the growth of III-V materials. High-resolution transmission electron microscopy (HRTEM) characterization shows Ge NMs crystallinity and high-resolution X-ray diffraction (HRXRD) reciprocal space mapping endorses high-quality GaAs layers. Finally, we demonstrate the chemical reconditioning process of the Ge substrate, allowing its reuse, to produce multiple free-standing NMs from a single parent wafer. The PEELER process significantly reduces the consumption of Ge during the fabrication process which paves the way for a new generation of low-cost flexible optoelectronics devices.Comment: 17 pages and 6 figures along with 3 figures in supporting informatio

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Metabolic changes in concussed American football players during the acute and chronic post-injury phases

<p>Abstract</p> <p>Background</p> <p>Despite negative neuroimaging findings many athletes display neurophysiological alterations and post-concussion symptoms that may be attributable to neurometabolic alterations.</p> <p>Methods</p> <p>The present study investigated the effects of sports concussion on brain metabolism using ¹H-MR Spectroscopy by comparing a group of 10 non-concussed athletes with a group of 10 concussed athletes of the same age (mean: 22.5 years) and education (mean: 16 years) within both the acute and chronic post-injury phases. All athletes were scanned 1-6 days post-concussion and again 6-months later in a 3T Siemens MRI.</p> <p>Results</p> <p>Concussed athletes demonstrated neurometabolic impairment in prefrontal and motor (M1) cortices in the acute phase where NAA:Cr levels remained depressed relative to controls. There was some recovery observed in the chronic phase where Glu:Cr levels returned to those of control athletes; however, there was a pathological increase of m-I:Cr levels in M1 that was only present in the chronic phase.</p> <p>Conclusions</p> <p>These results confirm cortical neurometabolic changes in the acute post-concussion phase as well as recovery and continued metabolic abnormalities in the chronic phase. The results indicate that complex pathophysiological processes differ depending on the post-injury phase and the neurometabolite in question.</p

First measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo Binary–Black-hole Merger GW170814

International audienceWe present a multi-messenger measurement of the Hubble constant H 0 using the binary–black-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in , which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km s−1 Mpc−1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km s−1 Mpc−1, we find (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0

Supplement: "Localization and broadband follow-up of the gravitational-wave transient GW150914" (2016, ApJL, 826, L13)

This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands