COUPLED THERMAL AND MECHANICAL EFFECTS IN INJECTED POLYMER PIECES: COMPARISON BETWEEN EXPERIMENTAL MEASUREMENTS AND NUMERICAL PREDICTION OF BOTH PRESSURE AND THERMAL CONTACT RESISTANCES TIME EVOLUTION

ABSTRACT During the cooling of an injected polymer, a very strong coupling exists between the thermal and mechanical phenomena. In order to fill in the mold and to compensate the effects of reduction of the thermal shrinkage, the pressure in the molding cavity is maintained to a very high level. The purpose of this paper is to show the essential importance of thermomechanical coupling present during the cooling of a hot polymer in a cold mold via a comparison between experiments and numerical simulation. Experiments show that the polymer-mold contact evolves under the effect of the internal contraction caused by the lowering of temperature. On the one hand, the air gap width, depending on the shape of the part, modifies the Thermal Contact Resistance (TCR) between the mold and the part. On the other hand, shrinkage is divided between the two sides of the part depending on the internal stresses, so that the geometry of the part is also linked to changing temperature. The resolution of the coupled thermal and mechanical problems allows us to predict the shape of the part, the stresses, the temperature field in the polymer and in the surrounding mold, and the air gap widths on both sides

Plasticity in the Sensitivity to Light in Aging: Decreased Non-visual Impact of Light on Cognitive Brain Activity in Older Individuals but No Impact of Lens Replacement

Beyond its essential visual role, light, and particularly blue light, has numerous non-visual effects, including stimulating cognitive functions and alertness. Non-visual effects of light may decrease with aging and contribute to cognitive and sleepiness complaints in aging. However, both the brain and the eye profoundly change in aging. Whether the stimulating effects light on cognitive brain functions varies in aging and how ocular changes may be involved is not established. We compared the impact of blue and orange lights on non-visual cognitive brain activity in younger (23.6 ± 2.5 years), and older individuals with their natural lenses (NL; 66.7 ± 5.1 years) or with intraocular lens (IOL) replacement following cataract surgery (69.6 ± 4.9 years). Analyses reveal that blue light modulates executive brain responses in both young and older individuals. Light effects were, however, stronger in young individuals including in the hippocampus and frontal and cingular cortices. Light effects did not significantly differ between older-IOL and older-NL while regression analyses indicated that differential brain engagement was not underlying age-related differences in light effects. These findings show that, although its impact decreases, light can stimulate cognitive brain activity in aging. Since lens replacement did not affect light impact, the brain seems to adapt to the progressive decrease in retinal light exposure in aging

Green Edge ice camp campaigns : understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies

Male Drosophila melanogaster flies exposed to hypergravity at young age are protected against a non-lethal heat shock at middle age but not against behavioral impairments due to this shock

Previous studies have shown that exposing flies to hypergravity (3 or 5g) for two weeks at young age slightly increases longevity of male flies and survival time at 37 °C of both sexes, and delays an age-linked behavioral change. The present experiments tested whether hypergravity could also protect flies from a non-lethal 37 °C heat shock applied at young, middle or old age (2, 4 or 6weeks of age). Various durations of exposure at 37 °C had similar deleterious effects on climbing activity, spontaneous locomotor activity and learning in flies that lived or not in hypergravity at young age. Therefore, hypergravity does not protect the behavior of flies from a deleterious non-lethal heat shock. Hypergravity increased longevity of virgin males and decreased that of mated ones; it also increased longevity of virgins at 25 °C, the usual rearing temperature, but not at 30 °C. Thus, the positive effect of hypergravity on longevity is observed only if flies are not subjected to living conditions decreasing longevity, like mating and high temperature. Finally, 4 weeks-old males that lived in hypergravity at young age lived slightly longer (+ 15%) after a non-lethal heat shock (60 or 90 min at 37 °C) than flies that always lived at 1 g, but this positive effect of hypergravity was not observed in females or in older males. Therefore, all these results show that hypergravity exposure can help male middle-aged flies recovering from a heat shock, but does not protect them from behavioral impairments linked to this shock: a mild stress occurring at young age can partially protect from a moderate stress at middle age. © 2004 Kluwer Academic Publishers.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Le chauffe-eau hybride électrique/photovoltaïque direct passera-t-il l’étape de la validation terrain?

Affiche présentée dans le cadre du colloque de l'ARC "Nouveaux enjeux pour la recherche collégiale" lors du 89e Congrès de l’Acfas, en ligne, le lundi 9 mai 2022Le Centre TERRE et ses partenaires développent depuis plus de deux ans le concept de chauffe-eau hybride électrique/solaire photovoltaïque en branchement direct, sans électronique sophistiquée. Le but est de réduire la consommation électrique du client avec un minimum d’investissement et d’impact environnemental. Par ailleurs, notre recherche s’ajoute aux efforts d’Hydro-Québec en vue de réduire les pics de consommation lors des périodes où la demande est forte. Les études technico-économiques, les essais préliminaires et la validation expérimentale en laboratoire ont été concluants. Les expériences au laboratoire ont démontré que les panneaux solaires contribuent au minimum pour 25 % de l’énergie électrique consommée par le chauffe-eau hybride et que cette contribution d’énergie par le solaire pourrait s’élever jusqu’à 80 %. Il y a donc un réel potentiel de réduction de la facture d’électricité des utilisateurs. Nous sommes à l’étape de la validation terrain à la suite de l’installation de deux prototypes de chauffe-eau dans deux résidences témoins situées à Montréal et au Saguenay, en collaboration avec notre partenaire industriel. La conception et l’affinement du design des chauffe-eau pilotes ont été faits à l’aide des logiciels Simpowersystems Matlab, Trnsys et Autocad Electrical. L’instrumentation intégrée sur les chauffe-eau pilotes permettra de valider par des données expérimentales la performance réelle de notre concept.(Acfas

Le droit de punir

En 1930, quelques années après avoir publié ses Souvenirs de la Cour d'assises, André Gide suggérait que la punition devrait tenir compte de la personnalité des criminels. Comment punir quelqu'un que l'on ne connaît pas ?, se demandait-t-il, ajoutant qu'« il est, sur la carte de l'âme humaine, bien des régions inexplorées ». Régulièrement, avec plus ou moins d'intensité, le droit de punir a été et reste l'objet de réflexions, de controverses, de propositions de loi, de demandes de réformes. Les débats sont tantôt vifs et profonds et semblent concerner le plus grand nombre, tantôt ils s'appauvrissent et restent réservés aux « spécialistes » qui dans des manuels ou des ouvrages d'histoire du droit pénal présentent ce dernier comme le droit de réprimer ou de sanctionner les auteurs d'infractions. Mais quel sens faut-il donner à la peine si elle n'est pas accompagnée d'autres mesures ? Est-elle une sorte d'horizon d'attente, une fiction des sociétés contemporaines qu'il faut bien entretenir ? Ne faut-il pas « remettre à plat » la justice pénale et se demander si après avoir puni il est possible de guérir ou de rendre un citoyen à la société ? La « pénalité » doit conserver son utilité écrivent les uns et les autres. Mais faut-il punir le crime ou plutôt les criminels ? Faut-il punir de la même manière les enfants, les fous et les récidivistes ? Que doit-on faire à l'époque de l'Empire français dans les colonies ? Ne conviendrait-il pas de se demander à nouveau pourquoi punir ? et de réfléchir à l'efficacité de la justice répressive ? La justice d'expiation et la « rédemption du coupable » ne suffisent pas, la peine est devenue aussi un enjeu symbolique et un moyen de communication, voire une « arme pénale ». Deux siècles après le Code pénal de 1810, une réflexion sur l'histoire du droit de punir et son actualité s'imposait, mais il fallait multiplier les approches disciplinaires, car le droit de punir ne relève pas seulement de considérations abstraites ou de joutes philosophiques. La pragmatique de la punition mérite aussi d'être examinée. Trois entrées ont donc été retenues (le droit de punir en question, connaître et pardonner, sanctionner les déviants) à partir du siècle des Lumières jusqu'à nos jours. Nul doute que l'histoire de la « punissabilité » permet de penser et de comprendre les sociétés du passé comme celle d'aujourd'hui

Green Edge ice camp campaigns: understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

International audienceThe Green Edge initiative was developed to investigate the processes controlling the primary productivity and the fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797N, 63.7895W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea ice cover from the surface to the bottom at 360 m depth to better understand the factors driving the PSB. Key variables such as temperature, salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, carbon stocks and fluxes were routinely measured at the ice camp. Here, we present the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in other Arctic studies. The dataset is available at http://www.seanoe.org/data/00487/59892/ (Massicotte et al., 2019a)

The MALINA oceanographic expedition: how do changesin ice cover, permafrost and UV radiation impactbiodiversity and biogeochemical fluxesin the Arctic Ocean?

International audienceThe MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. Dur- ing the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north) to capture the meridional gradient between the estuary and the open ocean.Key variables such as temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured onboard the Canadian research icebreaker CCGS Amundsen and from a barge in shallow coastal areas or for sampling within broken ice fields. Here, we present the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in further studies of the changing Arctic Ocean