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See detailVisco-plastic Chaboche model for nickel-based alloys under anisothermal cyclic loading
Morch, Hélène ULg; Morch, Hélène ULg; Duchene, Laurent ULg et al

in Proceedings of the XIV International Conference on Computational Plasticity (2017, September)

The mechanical behavior of visco-plastic materials such as nickel-based alloys is highly dependent on temperature. Some characteristics such as viscosity, hardening, static recovery, dynamic recovery have ... [more ▼]

The mechanical behavior of visco-plastic materials such as nickel-based alloys is highly dependent on temperature. Some characteristics such as viscosity, hardening, static recovery, dynamic recovery have more or less influence on the overall behavior depending on the considered temperature. The unified constitutive model developed by Chaboche [1] is very efficient in representing this complexity as it is very adaptable and can contain many features. A basic Chaboche model contains a viscosity law and one or several hardening equations. Within these hardening equations, it is possible to add several features that will represent the complex behavior of the material. The aim of this study is to understand the role of the different parameters and the influence of the different features in an advanced Chaboche model adapted to cyclic anisothermal loading. This specific model was also developed in [2],[3]. However, part of this study is based on particular cases where different features of the model are analyzed [4]–[6]. [less ▲]

See detailMultifunctional polyelectrolytes bearing catechol / quinone for applications in energy and environment
Patil, Nagaraj ULg

Doctoral thesis (2017)

The discovery of 3,4-dihydroxyphenyl-L-alanine (L-DOPA), a catechol-functionalized amino acid as major component in mussel adhesion proteins, has triggered enormous interest in mussel-mimetic adhesives ... [more ▼]

The discovery of 3,4-dihydroxyphenyl-L-alanine (L-DOPA), a catechol-functionalized amino acid as major component in mussel adhesion proteins, has triggered enormous interest in mussel-mimetic adhesives. The design of innovative bioinspired polymers-containing catechols has rapidly gained widespread utility in the (bio)material field, ascribed to the versatility of the catechol chemistry that allows anchoring (bio)polymers, biomolecules, nanoparticles (metals and metal oxides) and other compounds onto almost any kind of surfaces without any pre-treatment. Amongst the various synthetic protocols to incorporate catechol functionalities into (bio)polymers, the radical polymerization of catechol-bearing vinyl monomers in their protected form has proven to be a versatile technique to impart intrinsic physico–chemical properties of the catechol pendants to polymers after appropriate deprotection. Importantly, the scope of applications of catechol-bearing polymers can potentially be drastically increased by developing controlled radical polymerization (CRP) techniques of their protected vinyl monomers. Indeed, these techniques will enable to precisely design the polymer with the appropriate structure, molar mass and functionality that fit at best the target application. When this thesis started in 2013, only very limited examples of functional catechol-bearing polymers prepared by CRP were reported. The aim of this PhD thesis was to develop well-defined innovative catechol-containing (co)polymers that find applications in energy storage and environmental fields by employing function-oriented macromolecular engineering approaches. In this work, numerous catechol-protected monomers have been prepared and their CRP investigated to afford well-defined (co)polymers with controlled and tunable molar masses, compositions, functionalities, and architectures (homopolymers, statistical and block copolymers). The potential of these innovative catechol-containing (co)polymers was then explored for applications in energy storage (as active-material in lithium-ion half-cells) and environment (as protein fouling/antifouling coatings). [less ▲]

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See detailMultiple Uses of a 3D Point Cloud: the Castle of Franchimont (Province of Liège, Belgium)
Luczfalvy Jancsó, Andrea ULg; Jonlet, Benoît ULg; Hallot, Pierre ULg et al

Poster (2017, August 29)

This poster presents the identified obstacles, needs and selected solution for the study of the medieval castle of Franchimont, located in the province of Liège (Belgium). After taking into account the ... [more ▼]

This poster presents the identified obstacles, needs and selected solution for the study of the medieval castle of Franchimont, located in the province of Liège (Belgium). After taking into account the requirements from all the disciplines at work as well as the problems that would have to be tackled, the creation of a 3D point cloud was decided. This solution would be able to deal with the characteristics and needs of a research involving building archaeology and related fields. The decision was made in order to manage all of the available data and to provide a common working tool for every involved cultural heritage actor. [less ▲]

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See detailHigh-resolution reconstruction of 8.2 ka event recorded in Belgian Holocene speleothems
Allan, Mohammed ULg; verhyden, sophie; Fagel, Nathalie ULg

Scientific conference (2017, August 24)

Two abrupt shifts in d18O and trace element contents of a stalagmite from the northwestern European continent (southern Belgium) suggest that two cold anomalies occurred beginning at 8.4±0.04 and ending ... [more ▼]

Two abrupt shifts in d18O and trace element contents of a stalagmite from the northwestern European continent (southern Belgium) suggest that two cold anomalies occurred beginning at 8.4±0.04 and ending at 8.15±0.03, possibly reflecting climatic effects associated with the 8.2 ka event. The younger of the two anomalies lasted about 30 years, from 8.18 to 8.15±0.03 ka, with a maximum d18O amplitude of 1.4‰. Trace element (Sr, Ba and Mg) peaks coincide with this second drop of d18O. The anomaly initiation is marked by Sr, Ba and Mg concentration peaks suggesting drier conditions during the coldest years, consistent with previous research in the North Atlantic. The earlier anomaly in trace element, d18O records is associated with generally cold but wet conditions at 8.4 ka, lasted 50 years, and ended abruptly. The interval from 8.4 ka to 8.15 ka was less favorable for speleothem deposition, with denser speleothem calcite deposition and lower growth rate, consistent with a cold, dry climate. The clear recovery in both temperature and rainfall between after both anomalies (8.2 and 8.4 ka), suggests that these anomalies are distinct, and may represent two episodes of AMOC weaking related to the drainage of proglacial lakes Agassiz and Ojibway. [less ▲]

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See detailLandscape and hydrological controls on the downstream transport of dissolved organic matter in the Congo and Zambezi rivers
Lambert, T; Bouillon, S; Teodoru, CR et al

Conference (2017, August 20)

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See detailConstruction of high-resolution trace element time-series in Belgian speleothems by LA-ICP-MS
Allan, Mohammed ULg; verheyden, sophie; crucifix, michel et al

Conference (2017, August 17)

Speleothems, presented in Belgium, are now regarded as valuable archive of paelenvirenmental variations on the continents, offering a number of advantages relative to other continental climate proxy ... [more ▼]

Speleothems, presented in Belgium, are now regarded as valuable archive of paelenvirenmental variations on the continents, offering a number of advantages relative to other continental climate proxy recorders such as lake sediments. They are reliable continental archives of high interest due to their dating possibilities and their possibility to preserve multi-proxy records of environmental and climatic dynamics. Establishing high-resolution trace element time series in speleothems requires analytical techniques capable of representative sampling at sub-annual spatial resolution (on order of 22 µm in this study). In the Belgian Pere Noel cave (PN), high spatial resolution measurements of trace elements (e.g., Mg, Sr, Ba) were realized by using LA-ICP-MS and compared with results from lower resolution techniques (ICP-MS). The results from both techniques have been analysed in order to assess the capability of each technique to reconstruct climate changes at high resolution from PN stalagmite. Results showed that LA-ICP-MS technique allows a rapid analysis of multiple elemental concentrations, and uses minimal sample volume allowing for replicate sampling and availability of almost the entire original sample for other analyses. [less ▲]

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See detailCompositional gap at La Picada (CSVZ, Chile) results from critical cristallinity and compaction
Vander Auwera, Jacqueline ULg; Namur, Olivier ULg; Coumont, Valentin et al

Poster (2017, August 16)

Detailed reference viewed: 16 (1 ULg)
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See detailTwenty-year tracking of lighting savings and power density in the residential sector
Attia, Shady ULg

in Energy and Buildings (2017)

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See detailLa influencia normativa de China en América Latina y en el Caribe: ¿Un desafío estratégico para la Unión Europea?
Wintgens, Sophie ULg

Scientific conference (2017, August 16)

El crecimiento de los intercambios económicos y comerciales entre China y el subcontinente latinoamericano va acompañado de la imposición de normas económicas y políticas, de la cual su política de ... [more ▼]

El crecimiento de los intercambios económicos y comerciales entre China y el subcontinente latinoamericano va acompañado de la imposición de normas económicas y políticas, de la cual su política de comercio internacional es portadora. Esta constatación plantea la cuestión del desafío que esta influencia normativa china representa para la estrategia desplegada por la Unión Europea en América Latina y el Caribe. A fin de responder a esta cuestión, esta presentación contiene dos objetivos relacionados entre sí: por una parte, analizar el alcance normativo de la política comercial de China en ALC, con el fin de ver si ella es portadora de un proyecto político-económica regional comparable al modelo de integración y de gobernabilidad regional desplegado por la UE en el subcontinente latinoamericano; por otra parte, medir de la influencia de la producción normativa china en ALC a través de su capacidad para competir con las normas exportadas por la UE en esta región del mundo. [less ▲]

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See detail3D thermal finite element analysis of laser cladding processed Ti-6Al-4V part with microstructural correlations
Tran, Hoang Son ULg; Tchuindjang, Jérôme Tchoufack ULg; Paydas, Hakan ULg et al

in Materials & Design (2017), 128

In this study, a 3D thermal model of laser cladding by powder injection applied to Ti-6Al-4V is developed. The manufactured part is made of a Ti-6Al-4V substrate on which successive layers of laser melted ... [more ▼]

In this study, a 3D thermal model of laser cladding by powder injection applied to Ti-6Al-4V is developed. The manufactured part is made of a Ti-6Al-4V substrate on which successive layers of laser melted powder are added, leading to a thick deposit. The computed temperature field and its time evolution are compared to experimental measurements. The temperature distribution in the substrate allows the prediction of the depths of the melt pool and the heat affected zone. Correlations between simulated thermal histories and the final microstructure in the thick deposit are established, leading to the enhancement of a dynamic shift of the critical transformation points due to high thermal rates during laser processing. The nature of the phases present within the deposit is discussed. [less ▲]

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See detailInternet, vecteur d'un nouvel élan politique ?
Demelenne, Céline; Grandjean, Geoffrey ULg

Article for general public (2017)

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See detailSense-Making in Cyber Security - Examining Responder Behaviors in Cyber-Attacks
Tapanainen, Tommi ULg

in Proceedings of the Americas Conference on Information Systems (AMCIS) (2017, August 12)

Our understanding of the defense mechanisms against cyber-attacks is, to a great extent, based on preparation and deterrence. There is limited understanding, and in particular, limited evidence on how ... [more ▼]

Our understanding of the defense mechanisms against cyber-attacks is, to a great extent, based on preparation and deterrence. There is limited understanding, and in particular, limited evidence on how cyber security responders act to contain and recover from a cyber-attack. The actions of responders, including IT experts, corporate communications staff, and selected managers are critical. To address this gap, this research proposes applying the concept of sense-making, which has been extensively used to analyze human crisis behaviors. In this emerging research, we conduct an investigation into a cyber-attack case to shed light on the contextual and collective activities taken by responders in coping with cyber-attack response. We expect the results to validate or challenge theorizations of cyber security training and competencies from the communication and collaboration perspective. In a practical sense, our research can stimulate organizations to reflect on their own cyber security preparedness from the human perspective. [less ▲]

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See detailORBi : an institutional repository to promote Open Access
Chalono, Dominique ULg; Thirion, Paul ULg

Conference (2017, August 09)

Detailed reference viewed: 401 (3 ULg)
See detailState of Martian Upper Atmosphere as Observed by Imaging Ultraviolet Spectroscope Onboard MAVEN
Jain; Stewart; Deighan et al

Conference (2017, August 09)

NASA’s MAVEN spacecraft has taken more than two earth years (one Martian year) of observations of Mars to understand the process of Martian atmospheric evolution. The Imaging Ultraviolet Spectrograph ... [more ▼]

NASA’s MAVEN spacecraft has taken more than two earth years (one Martian year) of observations of Mars to understand the process of Martian atmospheric evolution. The Imaging Ultraviolet Spectrograph (IUVS) on board MAVEN observes Mars in far and mid ultraviolet (110-340 nm) with unique scanning and pointing capabilities, which are optimized for airglow studies. Dayglow emissions observed on Mars are a perfect tracer for the processes occurring in the emitting region of the atmosphere (100-200 km) and provide basic information about atmospheric composition (and its structure), and give insight into the dynamics, energetics, and physics and chemistry of the thermosphere. With its wide spatial and temporal coverage, IUVS observations of Martian dayglow has contributed immensely to our understanding of the Martian upper atmosphere and its response to incoming solar flux (EUV/FUV) and coupling between lower and upper atmosphere through tides and waves. In this presentation, I will talk about an overview of scientific results obtained by IUVS dayglow measurements, including (1) spatial/temporal distribution of major MUV and FUV emissions and their seasonal variability; (2) the seasonal variation of thermosphere temperatures inferred from dayglow measurements; (3) the effect of solar EUV flux (including the ~27-day solar rotation) and heliocentric distance on upper atmosphere temperature structure. We will present an overview of these results and a discussion of their implications for the state of the Martian upper atmosphere. [less ▲]

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See detailHydrogen Loss from Mars: Seasonal and Sourced from Upper Atmospheric Water
Chaffin; Deighan; Stewart et al

Conference (2017, August 09)

Mars has lost a significant fraction of its initial water inventory to space over its history. This loss proceeds via a chemical chain initiated in the lower and middle atmosphere below 100 km altitude ... [more ▼]

Mars has lost a significant fraction of its initial water inventory to space over its history. This loss proceeds via a chemical chain initiated in the lower and middle atmosphere below 100 km altitude, which results in H escape to space in the collisionless corona above about 200 km altitude. Hydrogen loss from Mars is tracked via brigtness measurements of this corona in Lyman alpha light at 121.6 nm, which is scattered by neutral H orbiting and escaping the planet. Here we present observations of H escape variability made by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission's Imaging Ultraviolet Spectrograph (IUVS) that demonstrate the seasonal dependence of H escape, adding to evidence initially gathered by Mars Express and the Hubble Space Telescope. We show that for two Mars years the atmosphere has exhibited enhanced H escape in Southern Summer near perihelion. We also present the result of photochemical model calculations which demonstrate that this variation can be explained as a result of high concentrations of water vapor in the upper atmosphere, consistent with Mars Express solar occultation measurements and several general circulation models. Our results demonstrate that the large variations in H escape at high altitudes can be driven by lower atmospheric dynamics, suggesting that Mars hydrogen escape may depend on climate, in addition to the long-term evolution of Martian climate depending on atmospheric escape. [less ▲]

Detailed reference viewed: 17 (0 ULg)