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See detailAerothermodynamics of Pre-Flight and In-Flight Testing Methodologies for Atmospheric Entry Probes
Sakraker, Isil ULg

Doctoral thesis (2016)

Spacecraft, returning back to Earth, experience a very harsh environment during the encounter with the particles of the atmosphere. One of the major issues of the atmospheric entry is the extreme ... [more ▼]

Spacecraft, returning back to Earth, experience a very harsh environment during the encounter with the particles of the atmosphere. One of the major issues of the atmospheric entry is the extreme aerodynamic heating and the exothermic chemical reactions due to the gas-surface interaction at hypersonic free stream velocities. There is a constant effort by the space agencies to increase the understanding of the re-entry flight dynamics to optimize the spacecraft and especially its thermal protection system design. During the design process, ground tests and numerical tools are extensively used for their low cost and controlled environment abilities. However, real flight tests are indispensable for ground test and numerical tools validation. Due to high costs, such missions are rarely launched and thus there is an increasing interest in small affordable entry probes. Such platforms, once matured enough, may serve as an easily accessible tool to produce experimental data. It is the aim of this dissertation to propose tools to improve ground test capabilities and on the other hand to present the design, and using the developed tools, the testing of aerothermodynamic experimental payloads to collect flight data with a small entry probe. QARMAN (QubeSat for Aerothermodynamic Research and Measurements on AblatioN) is a triple unit CubeSat with ablative and ceramic thermal protection systems. It will perform an atmospheric entry with 7.7 km/s and a peak heat flux of 1.7 MW/m2. The aim of the in-flight experiments is to retrieve real flight data on ablator efficiency (temperature, pressure, recession) and temperature-pressure measurements for transition on the side panels. The peculiar squared geometry of QARMAN led to the development of a Flight-to-Ground Duplication methodology accounting for spacecraft geometries. It allows duplicating fully the stagnation region of a spacecraft with an arbitrary geometry in subsonic plasma wind tunnels. As a requirement of this methodology, free stream characterization techniques, specifically enthalpy measurement techniques are introduced. Experimental and numerical databases are built. A thorough ablation characterization campaign in VKI Plasmatron is conducted to provide input for building material response models. The cork P50 ablator is studied in terms of surface and sub-surface temperatures, emissivity, mass loss, char-pyrolysis layers, outgassing species and recession and swelling profiles. Similar in-flight experiments are proposed for QARMAN flight for in-depth temperature and pressure. Methods to build models for advanced data treatment are proposed. A full picture of post-flight analysis strategy is described for each study to relate the ground tools and flight data. [less ▲]

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See detailMicrodélétions et duplications 22q11.22 distales
PIERQUIN, Geneviève ULg; CABERG, Jean-Hubert ULg; BULK, Saskia ULg

Poster (2016, February 03)

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See detailThe global chemistry climate model ECHAM6-HAMMOZ
Schultz, Martin G.; Franco, Bruno ULg; Kaffashzadeh, Najmeh et al

Poster (2016, February 02)

Atmospheric composition of short-lived gases and aerosols is an important component of the global climate system. Complex processes from emissions, transport, and chemical reactions to heterogeneous loss ... [more ▼]

Atmospheric composition of short-lived gases and aerosols is an important component of the global climate system. Complex processes from emissions, transport, and chemical reactions to heterogeneous loss processes and radiation interactions need to be implemented in climate models to reach an adequate understanding of the role of short-lived climate forcers on the climate system and to allow the assessment of climate impacts on the regional scale. With ECHAM6-HAMMOZ we have developed a comprehensive model of tropospheric and stratospheric aerosols and gas-phase chemistry which is now running successfully on the Jülich supercomputer JURECA. [less ▲]

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See detailArtificial Intelligence and Energy
Cornélusse, Bertrand ULg; Fonteneau, Raphaël ULg

Conference (2016, February 02)

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See detailDeciphering Mars lower atmosphere: Nitric Oxide nightglow seasonal variations as observed by IUVS
Stiepen, Arnaud ULg

Scientific conference (2016, February 02)

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See detailLa Chimie Biologique Industrielle à Gembloux Agro-Bio Tech
Berchem, Thomas ULg; Istasse, Thibaut ULg; Schmetz, Quentin ULg et al

Conference given outside the academic context (2016)

Présentation du laboratoire de Chimie Biologique Industrielle et illustration de nos principales activités; point sur les recherches de trois jeunes doctorants. Leur travail consiste en la valorisation de ... [more ▼]

Présentation du laboratoire de Chimie Biologique Industrielle et illustration de nos principales activités; point sur les recherches de trois jeunes doctorants. Leur travail consiste en la valorisation de matrices biologiques (déchets agricoles, industriels et forestiers,...) pour produire une gamme de nouveaux produits, biocarburants ou molécules chimiques. [less ▲]

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See detailLE PASSÉ, LE PRÉSENT ET L’AVENIR DE LA TRADUCTION AU CAMEROUN
Oumarou Mal Mazou, Rachid ULg

in Atelier de Traduction (2016), n°24

The inactement of institutional bilingualism by the Constitution exposes Cameroon to translation every day, as all official texts/speeches produced in one of the two official languages (French and English ... [more ▼]

The inactement of institutional bilingualism by the Constitution exposes Cameroon to translation every day, as all official texts/speeches produced in one of the two official languages (French and English) must be translated into the other. This translation demand requires translators and training of translators/interpreters becomes compulsory. First Cameroonian translators were initially trained in universities and colleges abroad and later on, after independence, at home when the Advanced School of Translators and Interpreters (ASTI) was created in the mid 1980s. The main objective of the school was to train translators/interpreters for public service. This goal will lapse when the Government decided not to enroll systematically ASTI graduates in 1999. Meanwhile, other private institutes as ISTI of Yaoundé, or programs like those of the University of Yaounde I opened their doors with curricula almost modeled on that of ASTI. Moreover, there is no regulation body for the profession, the only professional associtation that has been existing since the 90s is yet to find its way. This communication aims at looking into the development of translation in Cameroon from independence. Some suggestions are also made towards the future of the profession in one of the few countries where bilingualism is institutional and whereby about 300 local languages interact in a daily basis. [less ▲]

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See detailL'économie du partage
Gautier, Axel ULg

Conference given outside the academic context (2016)

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See detailDecreased antibiotic consumption in the Belgian community: Is it credible?
FRIPPIAT, Frédéric ULg; VERCHEVAL, Christelle ULg; LAYIOS, Nathalie ULg

in Clinical Infectious Diseases : An Official Publication of the Infectious Diseases Society of America (2016), 62(3), 403-404

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See detailFe XXV line profiles in colliding wind binaries
Rauw, Grégor ULg; Mossoux, Enmanuelle; Nazé, Yaël ULg

in New Astronomy (2016), 43

Strong wind-wind collisions in massive binaries generate a very hot plasma that frequently produces a moderately strong iron line. The morphology of this line depends upon the properties of the wind ... [more ▼]

Strong wind-wind collisions in massive binaries generate a very hot plasma that frequently produces a moderately strong iron line. The morphology of this line depends upon the properties of the wind interaction zone and its orientation with respect to the line of sight. As the binary components revolve around their common centre of mass, the line profiles are thus expected to vary. With the advent of the next generation of X-ray observatories (Astro-H, Athena) that will offer high-resolution spectroscopy above 6 keV, it will become possible to exploit these changes as the most sensitive probe of the inner parts of the colliding wind interaction. Using a simple prescription of the wind-wind interaction in an early-type binary, we have generated synthetic line profiles for a number of configurations and orbital phases. These profiles can help constrain the properties of the stellar winds in such binary systems. [less ▲]

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See detailDiversity and ecology survey of mosquitoes potential vectors in Belgian equestrian farms: A threat prevention of mosquito-borne equine arboviruses
Boukraa, Slimane ULg; de la Grandière, Maria Ana ULg; Bawin, Thomas ULg et al

in Preventive Veterinary Medicine (2016), 124

Emergence of West Nile Virus was recently recorded in several European countries, which can lead to severe health problems in horse populations. Europe is also at risk of introduction of mosquito-borne ... [more ▼]

Emergence of West Nile Virus was recently recorded in several European countries, which can lead to severe health problems in horse populations. Europe is also at risk of introduction of mosquito-borne equine alphavirus from Americas. Prevention of these arboviruses requires a clear understanding of transmission cycles, especially their vectors. To characterize mosquito fauna, their ecology and identify potential vectors of equine arboviruses in Belgium, entomological surveys of six equestrian farms located in the Wolloon Region were conducted during 2011–2012. The harvest of mosquitoes was based on larval sampling (272 samples from 111 breeding sites) and monthly adults trapping (CO2-baited traps, Mosquito Magnet Liberty Plus). Among 51,493 larvae and 319 adult mosquitoes collected, morphological identification showed the presence of 11 species: Anopheles claviger (Meigen), An. maculipennis s.l. (Meigen), An. plumbeus (Stephens), Culex hortensis (Ficalbi), Cx. territans (Walker), Cx. pipiens s.l. L., Cx. torrentium (Martini), Coquillettidia richiardii (Ficalbi), Culiseta annulata (Schrank), Aedes cantans (Meigen), Ae. geniculatus (Olivier). Molecular identification of Cx. pipiens species complex allowed the detection of three molecular forms, Pipiens (92.3%), Molestus (4.6%) and Hybrid (3.1%). Larvae of Cx. pipiens sl and Cx. torrentium were omnipresent and the most abundant species. Water troughs, ponds and slurry (liquid manure) were the most favorable breeding sites of mosquito larvae. Based upon behavior and ecology of the identified mosquito species, Studied Belgian equestrian farms seem to provide a suitable environment and breeding sites for the proliferation of potential vectors of arboviruses and those being a real nuisance problem for horses and neighboring inhabitants. [less ▲]

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See detailMeasuring rotation periods of solar-like stars using TIGRE. A study of periodic CaII H+K S-index variability
Hempelmann, A.; Mittag, M.; Gonzalez-Perez, J. N. et al

in Astronomy and Astrophysics (2016), 586

Context. The rotation period of a star is a key parameter both for the stellar dynamo that generates magnetic fields as well as for stellar differential rotation. <BR /> Aims: We present the results from ... [more ▼]

Context. The rotation period of a star is a key parameter both for the stellar dynamo that generates magnetic fields as well as for stellar differential rotation. <BR /> Aims: We present the results from the first year of monitoring a sample of solar-like stars by the TIGRE facility in Guanajuato (Mexico), which will study rotation in solar analogs. <BR /> Methods: TIGRE is an automatically operating 1.2 m telescope equipped with an Échelle spectrograph with a spectral resolution of 20 000, which covers a spectral range of between 3800 and 8800 Å. A main task is the monitoring the stellar activity of cool stars, mainly in the emission cores of the CaII H and K lines. We observed a number of stars with a sampling between 1-3 days over one year. <BR /> Results: A total number of 95 stars were observed between August 1 2013 and July 31 2014, the total number of spectra taken for this program was appoximately 2700. For almost a third of the sample stars the number of observations was rather low (less than 20), mainly because of bad weather. Fifty-four stars show a periodic signal but often with low significance. Only 24 stars exhibit a significant period. We interpret these signals as stellar rotation. For about half of them the rotation periods were already previously known, in which case our period measurements are usually in good agreement with the literature values. Besides the periodic signals, trends are frequently observed in the time series. <BR /> Conclusions: TIGRE is obviously able to detect stellar rotation periods in the CaII H+K emission cores when the time series contains a sufficient number of data points. However, this is frequently not achievable during the wet summer season in Guanajuato. Hence, future estimates of rotation periods will concentrate on stars that are observable during the winter season from October until April. [less ▲]

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See detailThe MiMeS survey of magnetism in massive stars: introduction and overview
Wade, G. A.; Neiner, C.; Alecian, E. et al

in Monthly Notices of the Royal Astronomical Society (2016), 456

The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in 2008 and ... [more ▼]

The MiMeS (Magnetism in Massive Stars) project is a large-scale, high-resolution, sensitive spectropolarimetric investigation of the magnetic properties of O- and early B-type stars. Initiated in 2008 and completed in 2013, the project was supported by three Large Program allocations, as well as various programmes initiated by independent principal investigators, and archival resources. Ultimately, over 4800 circularly polarized spectra of 560 O and B stars were collected with the instruments ESPaDOnS (Echelle SpectroPolarimetric Device for the Observation of Stars) at the Canada-France-Hawaii Telescope, Narval at the Télescope Bernard Lyot and HARPSpol at the European Southern Observatory La Silla 3.6 m telescope, making MiMeS by far the largest systematic investigation of massive star magnetism ever undertaken. In this paper, the first in a series reporting the general results of the survey, we introduce the scientific motivation and goals, describe the sample of targets, review the instrumentation and observational techniques used, explain the exposure time calculation designed to provide sensitivity to surface dipole fields above approximately 100 G, discuss the polarimetric performance, stability and uncertainty of the instrumentation, and summarize the previous and forthcoming publications. [less ▲]

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See detailThe α CrB binary system: A new radial velocity curve, apsidal motion, and the alignment of rotation and orbit axes
Schmitt, J. H. M. M.; Schröder, K.-P.; Rauw, Gregor ULg et al

in Astronomy and Astrophysics (2016), 586

We present a new radial velocity curve for the two components of the eclipsing spectroscopic binary α CrB. This binary consists of two main-sequence stars of types A and G in a 17.3599-day orbit ... [more ▼]

We present a new radial velocity curve for the two components of the eclipsing spectroscopic binary α CrB. This binary consists of two main-sequence stars of types A and G in a 17.3599-day orbit, according to the data from our robotic TIGRE facility that is located in Guanajuato, Mexico. We used a high-resolution solar spectrum to determine the radial velocities of the weak secondary component by cross-correlation and wavelength referencing with telluric lines for the strongly rotationally broadened primary lines (v sin(i) = 138 km s[SUP]-1[/SUP]) to obtain radial velocities with an accuracy of a few hundred m/s. We combined our new RV data with older measurements, dating back to 1908 in the case of the primary, to search for evidence of apsidal motion. We find an apsidal motion period between 6600 and 10 600 yr. This value is consistent with the available data for both the primary and secondary and is also consistent with the assumption that the system has aligned orbit and rotation axes. [less ▲]

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See detailMédecine de famille et prévention quaternaire. Conférence à l’Université Ouverte du Hainaut. Charleroi 1 février 2016
Jamoulle, Marc ULg

Conference (2016, February 01)

L’exposé est destiné aux seniors fréquentant l’Université du Temps disponible, soutenue par la Province du Hainaut, Belgique La médecin de famille ou médecine générale (MG/MF) est un métier complexe et ... [more ▼]

L’exposé est destiné aux seniors fréquentant l’Université du Temps disponible, soutenue par la Province du Hainaut, Belgique La médecin de famille ou médecine générale (MG/MF) est un métier complexe et méconnu qui demande de solides connaissances fondamentales en sciences de la vie mais aussi en sociologie et en anthropologie autant qu’en épidémiologie. La formation internationale européenne des MG/MF est rythmée dans l’exposé par la définition européenne qu’en donne l’association européenne des Médecins de famille (Wonca Europe) L’exposé, qui débute par une prise de position éthique et politique, est aussi émaillé de diapositives de l’auteur ou d’emprunt à la littérature internationale de médecine de famille et orné de détails de photographies prises par l’auteur. Humanisme et complexité sont les deux thèmes majeurs abordés. La deuxième partie de l’exposé est consacré à la Prévention quaternaire, concept inventé par l’auteur et qui incite les médecins et les patients à chercher une relation constructrice et à se garder des effets pervers de la médecine, tant symbolique que soi-disant scientifique, contrôlée par le profit et génératrice de surmédicalisation de la société. [less ▲]

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See detailExperimental and Numerical Characterization of Damage and Application to Incremental Forming
Guzmán Inostroza, Carlos Felipe ULg

Doctoral thesis (2016)

Nowadays, product manufacturing can be divided into two groups: relatively simple products produced in a large production chain and complex (specialized) components produced in reduced batches. Within the ... [more ▼]

Nowadays, product manufacturing can be divided into two groups: relatively simple products produced in a large production chain and complex (specialized) components produced in reduced batches. Within the second group, prototyping through incremental sheet forming (ISF) has been subject of several studies. ISF refers to processes where the plastic deformation occurs by repeated contact with a relatively small tool. A crucial aspect in the ISF processes is that the final shape is determined only by the tool movement. The focus of this research is the single point incremental forming (SPIF) process variant, where a clamped sheet metal is deformed by using a relatively small spherical tool. SPIF has several advantages over traditional forming, such as the high formability attainable by the material. Different hypothesis haven been proposed to explain this behavior, but there is still not a clear and definitive understanding of the relation between the particular stress and strain state induced in the material during SPIF and the material degradation leading to localization or fracture. In this thesis, a fundamental research is proposed using the finite element (FE) code LAGAMINE, developed within the University of Liège. Numerical implementation and validation of the Gurson-Tvergaard-Needleman (GTN) damage model into this FE code is performed. An experimental test campaign is developed to characterize plastic and damage behavior and to validate the damage model for the DC01 steel grade. Finally, this damage model is applied to simulate the SPIF process in order to verify if it is capable to predict failure. The thesis discusses the material parameter identification for classical plasticity models, describing the anisotropy and hardening behavior of the sheet metal. The derivation of the equations of the numerical damage model and the efficiency of the implementation is presented in great detail. A methodology for the numerical parameter identification of the damage model is proposed, including microscopic measurements by optical microscopy and strain and displacement field measurements by digital image correlation (DIC). The identified Gurson model is applied to simulate standard SPIF geometries, like the line, cone and pyramid tests. The simulations are performed using the solid-shell element formulation and validated in terms of shape and force prediction. Literature reviews of the Gurson model and the SPIF process are also included. The experimental results show that the selected material (DC01 steel sheet) exhibits a slight anisotropic behavior and work-hardening stagnation on cyclic tests. The performed microscopic measurements are not representative of the actual damage, but they give a qualitative estimation of the physical mechanism of fracture. The initial porosity of the material was determined using optical microscopy measurements in the base material. The numerical implementation of the model is developed with all variables integrated in an implicit way, based on the backward Euler scheme. Nucleation, coalescence and shear extensions implementations are validated by results obtained from the literature. The macroscopic campaign allowed to identify the parameters for nucleation, coalescence and shear. An unique set of results matching all experiments was not possible to obtain, so different sets of parameters are retrieved following an approach that includes inverse modeling and sensitivity analysis. A numerical-experimental comparison of strain values in the loading direction shows that the model is able to correctly predict the strain distribution except during localization of the strain. Globally, the obtained set of material parameters is in good agreement with the experimental results. For SPIF FE simulations, the results of the shape prediction are in good agreement with the experimental results, both for the line and pyramid test. Nevertheless, the force prediction is too high compared to reference values. On the other hand, the GTN model is capable to detect failure in a pyramid and a cone, but the prediction is too premature compared to the experimental failure angle for the same material and geometry. An accurate prediction of failure for the SPIF process was not possible to achieve. The GTN model extended to shear presents inherent flaws that prevent an accurate prediction of the failure angle for the SPIF process. Hence, an extensive research on the damage mechanisms leading to fracture for SPIF cannot rely (only) on the GTN model. The classical coalescence model of the GTN model is insufficient to correctly predict failure. Hence, it is recommended that further analysis concentrates on the description of this particular stage of damage evolution. During the development of this thesis, a robust implementation of the GTN model into the FE code LAGAMINE was done, including an extensive experimental database of microscopic and macroscopic measurements for the DC01 steel sheet. Other phenomena can be explored thanks to this model. [less ▲]

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