Simulation of the aeroelastic behavior of a possibly detached flow airfoil by a discrete vortex method

International audienceThe aeroelastic behavior of an airfoil results in a complex coupling between the elastic response of the structure and the dynamics of the flow. It can lead to the failure of a lifting surface which consequences could be catastrophic. Experiments and high-order computations contribute to the understanding of this phenomenon, but fast low-order methods are needed for engineering tasks. In the present work, we implement a loose fluid-structure coupling between a discrete-time vortex method, using a leading edge shedding criterion, and the structure motion equations. For each time step, the aerodynamic coefficients are first calculated before the computation of the motion of the structure. Flutter velocity is obtained with the same precision as unsteady standard method. The advantage of the method proposed is the ability to catch the limit cycle for velocities larger than flutter speed due to dynamic stall of the airfoil

Maîtriser la conception des drones solaires à voilure souple : vers l’avènement des pseudo-satellites à hautes altitudes (HAPS)

International audienceInitié dans les années 1950 avec l'invention des cellules photovoltaïques, le concept d'un drone solaire de haute altitude à endurance quasi-illimitée fait toujours l'objet d'une recherche active en raison de verrous technologiques persistants. La faible puissance propulsive extraite de la source solaire impose une architecture très particulière d'un tel aéronef avec notamment une voilure très allongée et très souple particulièrement vulnérable à des interactions destructrices. Ces dernières relèvent du domaine de l'aéroélasticité, discipline à l'interface entre l'aérodynamique et la mécanique des structures. Le présent article illustre ainsi l'approche nécessairement transdisciplinaire de ce défi technologique et présente des solutions innovantes issues de la recherche. Celles-ci devraient à terme permettre l'exploitation commerciale de ce concept capable de combler dans le domaine de l'observation et des télécommunications un creux capacitaire entre les actuels drones conventionnels de haute altitude et les solutions satellitaires. ABSTRACT. Initiated in the 1950s with the invention of photovoltaic cells, the almost unlimited endurance high altitude solar drone concept is still under heavy development because of persistent technological barriers. The low propelling power extracted from solar sources involves a specific design of an airframe consisting of a very lightweight and flexible airframe particularly vulnerable to destructive interactions. The latter fall within the scope of aeroelasticity, a discipline between aerodynamic and structural mechanics. This article illustrates the transdisciplinary approach required to achieve such a challenging goal and presents innovative solutions based on research work. These should enable commercial exploitation of such a concept and then fill the gap between conventional HALE drones and satellites in the field of observation and telecommunication. MOTS-CLÉS. Drone HALE, HAPS, énergie solaire, aéroélasticité, flutter, endurance

A DMAP-catalyzed mild and efficient synthesis of 1,2-dihydroquinazolines via a one-pot three-component protocol

International audienceAn efficient and simple method for the synthesis of 1,2-dihydroquinazolines catalyzed by 4-(N,N-dimethylamino) pyridine (DMAP) from readily available aromatic or heteroaromatic aldehydes, 2-aminobenzophenone, and ammonium acetate under mild conditions is described. The scope and limitations of the method are discussed

DNA Damage in Healthy Individuals and Respiratory Patients after Treating Whole Blood In vitro with the Bulk and Nano Forms of NSAIDs

YesNon-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX enzyme activity which affects the inflammatory response. Inflammation is associated with increasing cancer incidence. Pre-clinical and clinical studies have shown that NSAID treatment could cause an anti-tumor effect in cancers. In the present study, blood was taken from healthy individuals (n = 17) and patients with respiratory diseases or lung cancer (n = 36). White blood cells (WBC) were treated with either a micro-suspension, i.e., bulk (B) or nano-suspension (N) of aspirin (ASP) or ibuprofen (IBU) up to 500 μg/ml in the comet assay and up to 125 μg/ml in the micronucleus assay. In this study results were compared against untreated lymphocytes and their corresponding treated groups. The results showed, that NSAIDs in their nano form significantly reduced the DNA damage in WBCs from lung cancer patients in bulk and nano compared to untreated lymphocytes. Also, there was a decrease in the level of DNA damage in the comet assay after treating WBCs from healthy individuals, asthma and COPD groups with aspirin N (ASP N) but not with IBU N. In addition, the number of micronuclei decreased after treatment with NSAIDs in their nano form (ASP N and IBU N) in the healthy as well as in the lung cancer group. However, this was not the case for micronucleus frequency in asthma and COPD patients. These data show that lymphocytes from different groups respond differently to treatment with ASP and IBU as measured by comet assay and micronucleus assay, and that the size of the suspended particles of the drugs affects responses.The present study was part funded by United Kingdom India Education Research Initiative (UKERI) SA 07-067

V(D)J-mediated Translocations in Lymphoid Neoplasms: A Functional Assessment of Genomic Instability by Cryptic Sites

Most lymphoid malignancies are initiated by specific chromosomal translocations between immunoglobulin (Ig)/T cell receptor (TCR) gene segments and cellular proto-oncogenes. In many cases, illegitimate V(D)J recombination has been proposed to be involved in the translocation process, but this has never been functionally established. Using extra-chromosomal recombination assays, we determined the ability of several proto-oncogenes to target V(D)J recombination, and assessed the impact of their recombinogenic potential on translocation rates in vivo. Our data support the involvement of 2 distinct mechanisms: translocations involving LMO2, TAL2, and TAL1 in T cell acute lymphoblastic leukemia (T-ALL), are compatible with illegitimate V(D)J recombination between a TCR locus and a proto-oncogene locus bearing a fortuitous but functional recombination site (type 1); in contrast, translocations involving BCL1 and BCL2 in B cell non-Hodgkin's lymphomas (B-NHL), are compatible with a process in which only the IgH locus breaks are mediated by V(D)J recombination (type 2). Most importantly, we show that the t(11;14)(p13;q32) translocation involving LMO2 is present at strikingly high frequency in normal human thymus, and that the recombinogenic potential conferred by the LMO2 cryptic site is directly predictive of the in vivo level of translocation at that locus. These findings provide new insights into the regulation forces acting upon genomic instability in B and T cell tumorigenesis

Privatization and business groups: Evidence from the Chicago Boys in Chile

Business groups are the predominant organizational structure in modern Chile. This article tests the long-standing hypothesis that the privatization reform implemented by the “Chicago Boys” during the Pinochet regime facilitated the creation of new groups and hence the renovation of the country’s elites. Using new data we find that firms sold during this privatization later became part of new business groups, process aided by an economic crisis that debilitated traditional elites. Moreover, some firms were bought by Pinochet’s allies and were later used as providers of capital within groups. We conclude that privatizations can empower outsiders to replace business elites

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer, studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory, a versatile observatory designed to address the Hot and Energetic Universe science theme, selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), it aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over an hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR, browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters. Finally we briefly discuss on the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, and touch on communication and outreach activities, the consortium organisation, and finally on the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. (abridged).Comment: 48 pages, 29 figures, Accepted for publication in Experimental Astronomy with minor editin

The Athena X-ray Integral Field Unit: a consolidated design for the system requirement review of the preliminary definition phase

The Athena X-ray Integral Unit (X-IFU) is the high resolution X-ray spectrometer studied since 2015 for flying in the mid-30s on the Athena space X-ray Observatory. Athena is a versatile observatory designed to address the Hot and Energetic Universe science theme, as selected in November 2013 by the Survey Science Committee. Based on a large format array of Transition Edge Sensors (TES), X-IFU aims to provide spatially resolved X-ray spectroscopy, with a spectral resolution of 2.5 eV (up to 7 keV) over a hexagonal field of view of 5 arc minutes (equivalent diameter). The X-IFU entered its System Requirement Review (SRR) in June 2022, at about the same time when ESA called for an overall X-IFU redesign (including the X-IFU cryostat and the cooling chain), due to an unanticipated cost overrun of Athena. In this paper, after illustrating the breakthrough capabilities of the X-IFU, we describe the instrument as presented at its SRR (i.e. in the course of its preliminary definition phase, so-called B1), browsing through all the subsystems and associated requirements. We then show the instrument budgets, with a particular emphasis on the anticipated budgets of some of its key performance parameters, such as the instrument efficiency, spectral resolution, energy scale knowledge, count rate capability, non X-ray background and target of opportunity efficiency. Finally, we briefly discuss the ongoing key technology demonstration activities, the calibration and the activities foreseen in the X-IFU Instrument Science Center, touch on communication and outreach activities, the consortium organisation and the life cycle assessment of X-IFU aiming at minimising the environmental footprint, associated with the development of the instrument. Thanks to the studies conducted so far on X-IFU, it is expected that along the design-to-cost exercise requested by ESA, the X-IFU will maintain flagship capabilities in spatially resolved high resolution X-ray spectroscopy, enabling most of the original X-IFU related scientific objectives of the Athena mission to be retained. The X-IFU will be provided by an international consortium led by France, The Netherlands and Italy, with ESA member state contributions from Belgium, Czech Republic, Finland, Germany, Poland, Spain, Switzerland, with additional contributions from the United States and Japan.The French contribution to X-IFU is funded by CNES, CNRS and CEA. This work has been also supported by ASI (Italian Space Agency) through the Contract 2019-27-HH.0, and by the ESA (European Space Agency) Core Technology Program (CTP) Contract No. 4000114932/15/NL/BW and the AREMBES - ESA CTP No.4000116655/16/NL/BW. This publication is part of grant RTI2018-096686-B-C21 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. This publication is part of grant RTI2018-096686-B-C21 and PID2020-115325GB-C31 funded by MCIN/AEI/10.13039/501100011033

Apport de l’anisotropie des matériaux composites aux performances aéroélastiques des ailes à grand allongement de drones HALE

L'endurance d'un aéronef, correspondant à la durée maximale durant laquelle ce dernier peut rester en vol, est un paramètre fondamental pour caractériser la performance d'un plus lourd que l'air. Depuis l'apparition des panneaux photovoltaïques et leurs premières utilisations sur des aéronefs, l'idée d'une endurance virtuellement infinie, uniquement restreinte par des considérations de maintenance, fait son chemin au sein de la communauté aéronautique. Cette idée, matérialisée dans le concept de pseudo-satellite de haute altitude (High Altitude Pseudo-Satellite; HAPS) se heurte toutefois à des verrous technologiques persistants qui empêchent, aujourd'hui encore, son avènement malgré plusieurs décennies de recherche et développement. Parmi ces verrous, l'un des plus complexes à appréhender concerne la performance aéroélastique de ce type d'aéronef. En effet, la recherche drastique de performance, tant sur le plan aérodynamique et structural que sur la surface de captation solaire offerte, impose la conception de voilures à grand allongement extrêmement légères. Ces dernières sont alors nécessairement très souples, souplesse qui les rend particulièrement vulnérables à des interactions fluides/structures potentiellement destructrices comme le flottement ou la divergence statique en torsion. Les solutions classiques de conception, permettant de se prémunir de ces phénomènes dangereux, reposent principalement sur la modification de la répartition de masse et la rigidification des structures, ce qui pénalisent généralement le bilan de masse de l'aéronef et sont donc à proscrire. Dans ce contexte, l'utilisation des spécificités des matériaux composites, largement utilisés pour ce type de structure en raison de l'excellent rapport performance/masse qui les caractérisent, est une piste prometteuse. Parmi ces spécificités, l'anisotropie représente un choix intéressant dans la mesure où elle permet de coupler le comportement en flexion et en torsion d'une voilure et ainsi de modifier son comportement aéroélastique. Cette technique, appelée tissage aéroélastique, nécessite des outils de modélisation dédiés, à la fois pour prendre en compte l'anisotropie des matériaux employés et les grands déplacements et grandes rotations subies des structures très flexibles. Ce type de modèle, d'ordre réduit en raison du coût de calcul exorbitant que représenterait encore une approche haute fidélité, fait actuellement l'objet d'un effort de recherche important concourant à cette quête d'une endurance infinie. L'un de ces modèles d'ordre réduit, couplant une théorie de poutre anisotrope en grand déplacement et grande rotation à un modèle aérodynamique instationnaire, est développé dans ces travaux sous le nom de GEBTAero. Pour répondre au défi de complexité d'une voilure composite optimisée pour le concept de HAPS, l'accent est mis sur la performance de calcul et l'interopérabilité du modèle avec le choix d'une approche open source et son implémentation au sein d'une plateforme d'optimisation multidisciplinaire. La précision et la rapidité du programme sont évaluées à l'aide de cas tests issus de la littérature, en comparaison à d'autres modèles adaptés à cette physique. Ces résultats sont complétés par une campagne d'essais en soufflerie conduite à l'École de l'Air sur des plaques planes très souples, métalliques et composites, permettant ainsi à la fois de tester le code de calcul et d'abonder les résultats expérimentaux de la littérature. Le modèle est alors utilisé pour produire des solutions optimales de voilures à géométrie simple utilisant le tissage aéroélastique, mettant ainsi en valeur le gain substantiel de performance que cette technique permet.Aircraft endurance, which is the maximal duration of a flight, is a key feature of an heavier-than-air. Since the invention of photovoltaic cells and their first use on aircraft, the idea of a virtually infinite endurance, only restrained by maintenance issues, gain ground in the aviation community. This idea, materialised in the High Altitude Pseudo Satellite (HAPS) concept, is facing persistent technological barriers, preventing its achievement, despite decades of research and development. Among these barriers, one of the most complex to face is the aeroelastic performance of this type of aircraft. Indeed, the overwhelming need for performance in terms of aerodynamics, structures and available surface for solar cells, leads to the design of a lightweight high aspect-ratio wing. It results in a very flexible airframe, particularly vulnerable to destructive fluid/structure interactions like flutter or torsional divergence. Classical solutions designed to push further aeroelastic critical speed mostly rely on the stiffening of the airframe or the adjustment of mass distribution. Both options are detrimental to mass balance which is a key feature of HAPS. In that context, using composite materials specific features appears to be a suitable alternative. Among them is the anisotropy which is an interesting approach insofar as it permits the coupling of the bending and twisting behaviour of the wing and then to modify aeroelastic performances. This technology, namely the aeroelastic tailoring, requires specific modelling tools, for taking into account both material anisotropy and large displacement and rotation of the wing. The type of model, still of reduced order because of the prohibitive cost of a high fidelity model, is under extensive research since it contributes to the goal of an infinite endurance. One of theses reduced order models, coupling a large displacement and large rotation anisotropic beam theory with an unsteady aerodynamic theory is developed in this work. In order to face the challenge of a HAPS optimised airframe, a particular emphasis is being placed on its computation performance and interoperability, thanks to an open source implementation suitable for use within a multidisciplinary optimisation framework. Accuracy and computation speed are assessed using test cases from literature and compared to other suited reduced order models. These results were completed by a wind tunnel test campaign conducted in École de l'Air on flexible flat plate, both metallic and composite, thereby enabling both program testing and literature results contribution. Lastly, the model is used to produce a simple shape optimised wing, highlighting aeroelastic performance gains provided by this technology

Composite materials anisotropy contribution to aeroelastic properties of HALE drone high-aspect-ratio wings

L'idée d'un drone solaire haute altitude disposant d'une endurance virtuellement infinie, uniquement limitée par des questions de maintenance, fait sont chemin au sein de la communauté aéronautique. Toutefois, en raison de la faible puissance fournie par l'énergie solaire, ce concept nécessite l'utilisation d'une voilure à grand allongement très légère et donc très souple, ce qui la rend vulnérable à des phénomènes d'instabilités destructeurs comme le flottement ou la divergence en torsion. Ces travaux consistent à développer un code de calcul adapté à la physique complexe d'un tel aéronef, permettant d'exploiter les spécificités des matériaux composites pour éviter la présence de ces instabilités dans le domaine de vol. En complément de cas tests issus de la littérature, une campagne d'essais en soufflerie a été menée pour valider la performance du programme. Pour finir, sa capacité à être utilisé au sein d'une plateforme d'optimisation a été illustrée à travers un cas simple de plaque souple compositeThe idea of high altitude solar drones, with a virtually infinite endurance, only restrained by maintenance issues, gain ground in the aviation community. However, because of the low on-board power, this concept implies to design a very lightweight high aspect-ratio wing which is very flexible and then vulnerable to destructive instabilities like flutter or torsional divergence. This work consists in developing a computation code, namely GEBTAero, suitable for this type of airframe, allowing to exploit composite materials specificity to avoid such instabilities in the flight domain. Besides literature test cases, a wind tunnel campaign is conducted in order to validate the program performances. Lastly, its ability to be used within an optimisation framework is assessed with a simple shape composite flat plat