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See detailPharmacists' role in handling problems with prescriptions for atithrombotic medication in Belgian community pharmacies
Desmaele; De Wulf, I; Dupont, AG et al

in International Journal of Clinical Pharmacy [=IJCP] (2015), 37(4), 656-668

Background Community pharmacists have an important task in the follow-up of patients treated with antithrombotics. When delivering these medicines, pharmacists can encounter drug–related problems (DRPs ... [more ▼]

Background Community pharmacists have an important task in the follow-up of patients treated with antithrombotics. When delivering these medicines, pharmacists can encounter drug–related problems (DRPs) with substantial clinical and economic impact. Objective To investigate the amount and type of antithrombotic related DRPs as well as how community pharmacists handled these DRPs. Setting Belgian community pharmacies. Methods MSc pharmacy students of six Belgian universities collected data about all DRPs encountered by a pharmacist during ten half days of their pharmacy internship. Data were registered about DRPs detected at delivery and in an a posteriori setting, when consulting the medical history of the patient. Classification of the DRP, cause of the DRP, intervention and result of the intervention were registered. Main outcome measure Amount and type of antotrombitocs related DRPs occurring in community pharmacies, as well as how community pharmacists handled these DRPs. Results 3.1 % of the 15,952 registered DRPs concerned antithrombotics. 79.3 % of these DRPs were detected at delivery and 20.7 % were detected a posteriori. Most antithrombotic-related DRPs concerned problems with the choice of the drug (mainly because of drug–drug interactions) or concerned logistic problems. Almost 80 % of the antithrombotic-related DRPs were followed by an intervention of the pharmacist, mainly at the patient’s level, resulting in 90.1 % of these DRPs partially or totally solved. Conclusion Different DRPs with antithrombotic medication occurred in Belgian community pharmacies. About 20 % was detected in an a posteriori setting, showing the benefit of medication review. Many of the encountered DRPs were of technical nature (60.7 %). These DRPs were time-consuming for the pharmacist to resolve and should be prevented. Most of the DRPs could be solved, demonstrating the added value of the community pharmacist as first line healthcare provider. [less ▲]

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See detailOpérations militaires : entre prise de risque, solidarité, souveraineté et "entrée en premier"
Dumoulin, André ULg

in Sécurité & Stratégie (2015), (201),

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See detailShort-term responses of glass eels transported from UK to small Belgian streams
Ovidio, Michaël ULg; Tarrago-Bes, Frédérique; Nzau Matondo, Billy ULg

in Annales de Limnologie = International Journal of Limnology (2015), 51(3), 219-226

Restocking of inland waters with glass eels is one of the recovery options to prevent the decline of European eel Anguilla anguilla (L.) populations. We studied the growth, dispersion, density and habitat ... [more ▼]

Restocking of inland waters with glass eels is one of the recovery options to prevent the decline of European eel Anguilla anguilla (L.) populations. We studied the growth, dispersion, density and habitat preferences in the imported glass eels from United-Kingdom and stocked in three typologically different small Belgian streams, using electrofishing surveys around the single release point, 1 year following stocking. Our results clearly support that the recaptured individuals stocked in our streams farther from the sea, survived, grew, dispersed upstream and downstream. Elvers exploited the complete transversal section of stream, with preference for the sheltered microhabitats near the banks with slower water velocity and low depth. Length-weight relationship was different between streams in terms of allometric coefficient (b). We assume that microhabitats and food availabilities lead to contrasted results in terms of growth and absolute occurrence. Restocking of glass eels in small middle-land streams was found to be an interesting and unconventional option that requires adequate stream and habitat selection. [less ▲]

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See detailNiche-innovations between breaks and continuities with the regime? A case study into the dairy sector in Belgium
Feyereisen, Marlène ULg; Melard, François ULg; Stassart, Pierre M ULg

Conference (2015, August)

Today, the absolute dichotomy between alternative food networks (AFNs) and the conventional agrofood system tends to be obsolete. Indeed, many AFNs are far from being radical and are more likely to ... [more ▼]

Today, the absolute dichotomy between alternative food networks (AFNs) and the conventional agrofood system tends to be obsolete. Indeed, many AFNs are far from being radical and are more likely to maintain relations with the current socio-technical regime between breaks and continuities. This contribution is a complement to the Transition Theory and the Multi-Level Perspective by underlying the fragile borders between the two levels of the niche-innovations and the socio-technical regime: some imperfect projects, full of contradictions, are participating to the transition of the system. And this is particularly true in the case of highly locked in systems. The dairy sector in Western European countries is one of those highly locked in systems. Our case study, the Belgian fair-trade milk “Fairebel”, is a project built by dairy farmers to react to the 2009 dairy crisis and to the increasingly neoliberal dairy sector; and to get a better price (or fair price) for their activity. However, the concretization of this project brought its share of contradictions regarding the common definition of fair trade milk. As a result, the “Fairebel” project maintains relations between breaks and continuities with the regime. This contribution suggests modes of governance for the stakeholders of these non-radical niches which are precious to engage change in highly locked in system without being picked up by the dominant regime and thus, keep this regime under pressure. [less ▲]

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See detailReduced Order Modeling Techniques in Experimental Dynamic Substructuring
Roettgen, Dan; Dossogne, Tilàn ULg; Seeger, Benjamin et al

Poster (2015, August)

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See detailAgriculture Seen Through the Prism of the French Media in Belgium
Dubois, Charline ULg

in Firmino, Ana (Ed.) Smart answers for a smiling future (2015, August)

Scholars agree on the importance of the farming activities to maintain the quality (aesthetic environment) of rural areas. The number of farmers in Belgium fall steadily in the recent decades (Van Hecke ... [more ▼]

Scholars agree on the importance of the farming activities to maintain the quality (aesthetic environment) of rural areas. The number of farmers in Belgium fall steadily in the recent decades (Van Hecke et al. 2010). In particular, the rural systems of Wallonia transformed, characterized by the increased presence of landscapes of consumption and the influx of urban migrants. Why do they live in the countryside? Do they know the farmers in the area? What are the rural idylls (Yarwood 2005)? The answers to these questions lead to the understanding of perceptions and recognitions of rural spaces among different stakeholders. On another scale, this leads to the need for the improvement of social and territorial cohesion to improve the quality of life and the integration of people into their new living environment. The topics about “to live and to build the countryside” are current (Cawley & Gillmor 2008, Frelat-Kahn & Lazzarotti 2012) and are also concerned with the future of the countryside, of farming, and of the vitality of rural systems that face challenges according to geographic situations. With increasing suburbanization and multifunctionality (Bills & Gross 2005), some inhabitants want to build an interdependent community with authentic values. But the inhabitants’ representations about rural way of life are inexistent (despite some local initiatives such as organic produces) or complex (Dubois & Schmitz 2011, Tencati & Zsolnai 2012). Each person can say that he/she lives in the countryside by considering different space realities, with the risk that farmers could become strangers (Simard & Guimond 2013)! “Each year we organised a party in our street with everybody from the surrounding areas. Some farmers come and it is amazing to socialize more than just pass each other by cars and tractors” (inhabitant in a rural town in Wallonia). This study presents a first step in exploring inhabitant’s representations of the countryside. We analyse here the organic image about agriculture developed by the media that partly influences the people's perception of agriculture. Other than the induced and experienced images, organic image or “those that arise from supposedly unbiased sources” such as books, school education, television, documentaries, newspapers, and word of mouth (Gunn 1972, O'Leary & Deegan 2005) is considered. “People are interested about agricultural features. We speak a lot about that in the media, so people would like to know more about us and our job! That is why they visit us and they are sometimes so disoriented!” (Farmer in Wallonia). The analysis focuses on 3 consecutive even-numbered years: 2010, 2012 and 2014, from January to December. The national online press platform was used to access the articles. This allows for an analytical look at how agriculture is represented in the newspapers: What themes were addressed? How often? And to know the level of importance, in which part of the newspapers did it appear? The study analysed articles from 2 Belgian French newspapers from different media groups (Le Soir, La Libre). Different regions were covered to take into account different agro-geographical landscapes, suburban and rural features of the countryside, and different social and economical realities of Wallonia. For each article, topic selection and content analysis (NVivo ) were undertaken. Bette (2012) made the first analysis of the topic in 2012 and put into evidence 13 different categories in which agriculture has been presented: organic, diversification, legislation, economy, crops, farming, food, biotechnology, energy, animal health, plant diseases, environment, other. However, for this research, we improved the typology and add other topics such as the tourism, the local produces, the (agro-) geographical regions. Qualitative analysis showed that economic difficulties, economic investment, local produces, slow food, European policies, environment are among the categories frequently explored. All the different categories were represented and were often sensationalised but the level of importance is not high as most news were often found inside the newspaper and not on the front page. These different elements influence the representations of the different readers and give an overview about the influence of images of agriculture on the inhabitants. Agriculture is related to multiple components but some of these aspects are not presented and remain unknown to the common public. A lot of other questions about agricultural and rural systems and agricultural regions are not covered because on-going social, economic environmental and cultural trends tend to influence the information that are found in the newspapers. Agriculture is often simplified in a positive (e.g. local products, organic farming) and in a negative way (e.g. pollutions, bankruptcies, suicides) which implied that it is difficult for laymen to have a valid representation based on newspapers. [less ▲]

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See detailBifurcation Analysis of a Spacecraft Structure Using the Harmonic Balance Method
Detroux, Thibaut ULg; Renson, Ludovic ULg; Masset, Luc ULg et al

in Proceedings of the ASME 2015 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE 2015) (2015, August)

The harmonic balance (HB) method has been widely used in the past few years, as a numerical tool for the study of nonlinear models. However, in its classical formulation the HB method is limited to the ... [more ▼]

The harmonic balance (HB) method has been widely used in the past few years, as a numerical tool for the study of nonlinear models. However, in its classical formulation the HB method is limited to the approximation of periodic solutions. The present paper proposes to extend the method to the detection and tracking of bifurcations in the codimension-2 system parameters space. To validate the methodology, the forced response of a real spacecraft is examined. The paper first provides some numerical evidence of the presence of quasiperiodic oscillations and isolated solutions. It then demonstrates how the tracking of Neimark-Sacker and fold bifurcations can help get a deeper understanding of these attractors. [less ▲]

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See detailDesign, Modeling, and Performance Optimization of a Reversible Heat Pump/Organic Rankine Cycle System for Domestic Application
Quoilin, Sylvain ULg; Dumont, Olivier ULg; Harley Hansen, Kristian et al

in Journal of Engineering for Gas Turbines and Power (2015)

In this paper, an innovative system combining a heat pump (HP) and an organic Rankine cycle (ORC) process is proposed. This system is integrated with a solar roof, which is used as a thermal source to ... [more ▼]

In this paper, an innovative system combining a heat pump (HP) and an organic Rankine cycle (ORC) process is proposed. This system is integrated with a solar roof, which is used as a thermal source to provide heat in winter months (HP mode) and electricity in summer months (ORC mode) when an excess irradiation is available on the solar roof. The main advantage of the proposed unit is its similarity with a traditional HP: the HP/ORC unit only requires the addition of a pump and four-way valves compared to a simple HP, which can be achieved at a low cost. A methodology for the optimal sizing and design of the system is proposed, based on the optimization of both continuous parameters such as heat exchanger size or discrete variables such as working fluid. The methodology is based on yearly simulations, aimed at optimizing the system performance (the net yearly power generation) over its whole operating range instead of just nominal sizing operating conditions. The simulations allow evaluating the amount of thermal energy and electricity generated throughout the year, yielding a net electric power output of 3496 kWh throughout the year. [less ▲]

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See detailLa lutte contre les moustiques (Diptera: Culicidae): diversité des approches et application du contrôle biologique
Bawin, Thomas ULg; Seye, Fawrou; Boukraa, Slimane ULg et al

in Canadian Entomologist (2015), 147(4), 476-500

Many mosquito (Diptera: Culicidae) species are zoonotic vectors responsible for numerous infectious diseases of medical and veterinary importance. Currently, changes in the vectors’ geographical ... [more ▼]

Many mosquito (Diptera: Culicidae) species are zoonotic vectors responsible for numerous infectious diseases of medical and veterinary importance. Currently, changes in the vectors’ geographical distribution induced chiefly by anthropogenic factors are accompanied by emerging and reemerging infectious diseases in Europe and North America. Since the advent of synthetic insecticides during the Second World War, mosquitoes are the object of considerably expanded and deepened research. In an integrated pest management context, means of control are now mainly classified as: (1) environmental management and physical control, (2) chemical control, (3) genetic control, and (4) biological control by means of entomophagous predators and entomopathogenic microorganisms. In this context, these last have significant potential because of their ability to infect and kill their host with more or less targeted selectivity. This article proposes to emphasize biological control among other techniques in mosquito control, and to assess the potential and the opportunities offered by entomopathogenic bacteria, viruses and fungi. Finally, their use as biopesticides is discussed. [less ▲]

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See detailStudies of nebulae ejected from massive stars based on observations with the Herschel space observatory
Vamvatira-Nakou, Chloi ULg

Doctoral thesis (2015)

This PhD thesis is devoted to the study of the nebulae ejected by the luminous blue variable (LBV) stars WRAY 15-751 and AG Car as well as by the Wolf-Rayet star WR 124. It is based on new infrared data ... [more ▼]

This PhD thesis is devoted to the study of the nebulae ejected by the luminous blue variable (LBV) stars WRAY 15-751 and AG Car as well as by the Wolf-Rayet star WR 124. It is based on new infrared data taken by the Herschel Space Observatory. These data were complemented by optical data as well as by archived infrared observations. In the first chapter, a general introduction to the subject is given along with a description of the methods used for the data analysis. The three following chapters contain the study of each one of the three nebulae separately. This led to the determination of the physical parameters of the dust and gas components, with the aim to shed a new light on the mass-loss history of the central stars. In particular, the new Herschel infrared images provide a detailed mapping of the nebular dust distribution and of the circumstellar environment at different scales, revealing multiple shells and cavities linked to previous mass-loss events. Moreover, the combination of Herschel photometric results along with archival data was used to model dust with the help of a two-dimensional publicly available radiative transfer code. This model provided us with the dust mass, temperature and composition. The Herschel infrared spectra of all nebulae revealed forbidden nebular emission lines coming not only from an ionized gas region but also from a region where the gas is neutral. Based on the emission line flux measurements, the gas mass and the abundance ratios were estimated. These results, combined with the theoretical models of stellar evolution, were then used to constrain the evolutionary stage of the star at which each nebula was ejected. This study underlines the importance of the Herschel infrared observations for these nebulae. Thanks to them, a better understanding of these objects has been achieved. In particular, a second bigger and fainter dust shell was discovered around WRAY 15-751. In addition, all nebulae were found lying in empty cavities, probably formed during a previous evolutionary phase of their central star. The dust models indicated the necessity to include large grains in all nebulae to reproduce the data. This study showed that for the LBV WRAY 15- 751, with an initial mass of 40 M sun, the nebular ejection took place during a red supergiant phase, while for the LBV AG Car, with an initial stellar mass of 55 M sun, the ejection happened during a cool LBV phase. For the nebula M1-67 around the star WR 124, with an initial mass of 60 M sun, the ejection also took place during a LBV phase. These results are in agreement with the current evolutionary models with little stellar rotation. [less ▲]

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See detailGouvy Jazz & Blues Festival Août 2015
Sacré, Robert ULg

E-print/Working paper (2015)

Compte rendu du festival BLUES avec photos

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See detailLe Parc National Sahamalaza - Iles Radama serait-il l’ultime refuge pour certaines espèces de lémuriens du nord-ouest de Madagascar ?
Wilmet, Leslie ULg; Beudels-Jamar, Roseline C.; Schwitzer, Christoph et al

in Tropicultura (2015)

Depuis des millions d’années, la faune et la flore terrestre de Madagascar ont évolué dans un espace isolé. Suite à cette situation, le niveau d’endémisme y est très élevé et l’ensemble de l’île ... [more ▼]

Depuis des millions d’années, la faune et la flore terrestre de Madagascar ont évolué dans un espace isolé. Suite à cette situation, le niveau d’endémisme y est très élevé et l’ensemble de l’île représente un des plus importants hotspot de biodiversité. Madagascar fait aussi partie des pays les plus touchés en termes de destruction des habitats naturels ; 90 % de la végétation d’origine est aujourd’hui perdue. La déforestation et la fragmentation des habitats forestiers menace particulièrement les primates de l’île, les lémuriens. L’île est considérée par de nombreuses organisations internationales comme une priorité pour la conservation de la nature, autant dans le domaine zoologique que botanique. Les premières aires protégées de Madagascar ont été établies en 1927 et l’île en compte aujourd’hui 47. Cet article reprend l’historique et fait l’état des lieux du parc national Sahamalaza-Ile Radama, situé au nord-ouest de Madagascar. Nous nous intéressons spécifiquement à deux espèces de lémuriens emblématiques du parc ; Eulemur flavifrons et Lepilemur sahamalazensis ainsi qu’aux menaces qui pèsent sur leur écosystème. Différentes mesures ont été proposées dans le cadre d’un Plan d’Action de Conservation afin d’en améliorer la gestion et assurer la survie de ces espèces. [less ▲]

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See detailThe effects of triclosan exposure in shape changes of sheepshead minnow (Cyprinodon variegatus) during early development and metamorphosis
Schnitzler, Joseph ULg; Frederich, Bruno ULg; Dussenne, Mélanie et al

Conference (2015, August)

Thyroid hormones are essential for normal development, and for maintenance of normal physiological functions in vertebrates [1, 2]. In fish, thyroid hormones are involved in the control of osmoregulation ... [more ▼]

Thyroid hormones are essential for normal development, and for maintenance of normal physiological functions in vertebrates [1, 2]. In fish, thyroid hormones are involved in the control of osmoregulation, metabolism, somatic growth and post-hatching metamorphosis [1, 3, 4]. The regulation of thyroid hormone bioavailability in tissues and cells represents a very complex and unique web of feedback systems [2]. In fish and other vertebrates the thyroid cascade involves two components. First, thyroxine (T4) biosynthesis and secretion are largely under central control by the brain–pituitary–thyroid axis [5]. Second, there is the conversion of T4 to its biologically active form 3,5,3-triiodothyronine (T3) and its metabolism and receptor-mediated actions that seems largely to be under peripheral control in extra-thyroidal tissues [6]. The accumulation in the aquatic environment of anthropogenic chemicals, among which are endocrine disrupting chemicals (EDCs) that alter normal hormonal regulation, is having dramatic consequences for humans and wildlife. Numerous chemicals disrupt thyroid homeostasis affecting thyroid hormone (TH) synthesis and transport, and cellular uptake and metabolism [7, 8]. Triclosan (TCS) is a synthetic chlorinated phenolic compound with a generalized use as an antimicrobial and preservative in many personal care and household products [9-11]. As a result of disposal of TCS through sewage systems and insufficient/variable removal by wastewater treatment plants (WWTP) [9], widespread contamination with TCS has been detected in several countries, particularly in aquatic ecosystems, WWTP influents and effluents; sludges and biosolids; surface or ground water; drinking water; and aquatic sediments [9-11]. TCS and its metabolites have been detected in tissues and body fluids of aquatic organisms including fish, revealing they are accumulating in the food chain [9-11] and TCS has also been detected in human blood, breast milk and urine [9-11]. The structural similarity of TCS with THs [9] suggest it may have adverse effects on the thyroid system. However, little is known about the mechanisms by which TCS disrupts the thyroid axis. TCS effects on fish thyroid axis have not been investigated. It is possible, that the TCS toxic effects reported in fish embryos, larvae and adults [9-11] might be caused, at least in part, through its effect on the thyroid system. We determined how TCS affect ontogenic variations of thyroid hormones in developing sheepshead minnow larvae. Knowing that thyroid hormones are involved in somatic growth and post-hatching metamorphosis, we also tested the hypothesis that TCS alter the development of these larvae. To do this, we used landmark-based geometric morphometric methods. These methods allowed us to analyse the pure shape variations of our developing larvae, regardless orientation, position, and size. [less ▲]

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See detailDo Triclosan affect hearing development of Cyprinodon variegatus larvae?
Schnitzler, Joseph ULg; Benichou, Farida; Pinte, Nicolas et al

Poster (2015, August)

The aquatic environment represents the final sink for many chemicals, including bactericidal agents. Among them Triclosan (TCS) has been shown to affect the thyroid system of teleost. Larval stages are ... [more ▼]

The aquatic environment represents the final sink for many chemicals, including bactericidal agents. Among them Triclosan (TCS) has been shown to affect the thyroid system of teleost. Larval stages are particularly vulnerable to deleterious effects of endocrine disrupters because of potential impairment of fish development and behaviour. Thyroid hormones are critical to the development of the brain and auditory system. Thus, TCS could affect the development of the brain and hearing. The aims of this study were: to investigate hearing development in sheepshead minnows (Cyprinodon variegatus) using the ABR technique (Auditory Brainstem Response) and to investigate the effects of triclosan on hearing development. Exposure to TCS was conducted from fertilization of eggs on at concentrations likely to be found in the environment: 20, 50 and 100 µgl-1. We characterized previously the ontogenic variation of thyroid hormones in embryos and larvae of sheepshead minnows. We observed an increase of thyroid hormones level around the 12th and the 15th day post hatching (dph), that may be associated with the transition from larval to juvenile stage during the development of this species. We concluded, that this period could be defined as a critical exposure window to pollutants. We determined hearing thresholds for sheepshead minnows of different ages. Our sheepshead minnows show ontogenic variations in the hearing ability during their development. At 30 days post hatching, their hearing ability is quite bad, with a narrow bandwidth of detected frequencies. But their hearing ability considerably enhance during their development to reach the adult hearing ability at around 80 days post hatching when this species reach sexual maturity. So we observe during the developmental phase of this fish species clear ontogenic improvements of the hearing ability and they showed an ontogenetic expansion in the frequency bandwidth they were able to detect. The effects of TCS in this development have yet to be determined but will be fully discussed. This study proposes an interesting new endpoint in thyroid disruption research. [less ▲]

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See detailLe monopole de la légitimité démocratique
Debras, François ULg

in Revue de la Faculté de Droit de l'Université de Liège (2015), 2

Loin d’être le résultat de facteurs externes, la contestation du régime démocratique semble être avant tout le résultat d’une critique inhérente au système. Différents indicateurs mesurables viennent ... [more ▼]

Loin d’être le résultat de facteurs externes, la contestation du régime démocratique semble être avant tout le résultat d’une critique inhérente au système. Différents indicateurs mesurables viennent étayer ce que certains auteurs qualifient de « syndrome de fatigue démocratique » ou encore de « corruption du régime constitutionnel pluraliste », tels que l’augmentation de l’abstentionnisme durant les périodes électorales, une volatilité et une instabilité croissante de l’électorat et une baisse des adhésions aux organisations collectives. Fait tout aussi significatif, il semblerait que les jeunes démocraties dans les pays de l’ex-Union soviétique, d’Asie ou d’Amérique latine n’échappent pas non plus à ces phénomènes. Cette situation illustre-t-elle une perte de légitimité démocratique, une crise démocratique ou ne correspond-elle pas plutôt à une volonté citoyenne de transformer nos démocraties en élargissant et en approfondissant certaines de ses dynamiques et procédures qui lui sont propres ? Pour répondre à cette question, nous proposons de nous concentrer sur trois éléments distincts, mais étroitement liés au sein de nos démocraties européennes au XXIe siècle : le lien représentant/représenté (la représentation), la reconnaissance des libertés individuelles vis-à-vis de l’organisation collective de la société (les citoyens) et l’action du pouvoir étatique (l’État). [less ▲]

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See detailPerformance, robustness and sensitivity analysis of the nonlinear tuned vibration absorber
Detroux, Thibaut ULg; Habib, Giuseppe ULg; Masset, Luc ULg et al

in Mechanical Systems & Signal Processing (2015), 60-61

The nonlinear tuned vibration absorber (NLTVA) is a recently developed nonlinear absorber which generalizes Den Hartog׳s equal peak method to nonlinear systems. If the purposeful introduction of ... [more ▼]

The nonlinear tuned vibration absorber (NLTVA) is a recently developed nonlinear absorber which generalizes Den Hartog׳s equal peak method to nonlinear systems. If the purposeful introduction of nonlinearity can enhance system performance, it can also give rise to adverse dynamical phenomena, including detached resonance curves and quasiperiodic regimes of motion. Through the combination of numerical continuation of periodic solutions, bifurcation detection and tracking, and global analysis, the present study identifies boundaries in the NLTVA parameter space delimiting safe, unsafe and unacceptable operations. The sensitivity of these boundaries to uncertainty in the NLTVA parameters is also investigated. [less ▲]

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See detailAtmospheric circulation changes identified thanks to ground-based FTIR monitoring of hydrogen chloride (HCl)
Mahieu, Emmanuel ULg; Chipperfield, Martyn. P.; Notholt, Justus et al

Article for general public (2015)

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See detailPhysical modeling of lateral dike breaching due to overtopping
Rifai, Ismail; Erpicum, Sébastien ULg; Archambeau, Pierre ULg et al

in River, Coastal and Estuarine Morphodynamics, RCEM 2015 (2015, August)

Dikes are commonly used as defense structures for river flow channelization, protecting population and property from floods and against lateral riverbed migration. However, the aging of these structures ... [more ▼]

Dikes are commonly used as defense structures for river flow channelization, protecting population and property from floods and against lateral riverbed migration. However, the aging of these structures, combined with their increased vulnerability to extreme hydrological events may cause the dikes to breach, and subsequently to break. Furthermore, statistics show that flow overtopping is the main cause of dike failure, which emphasizes the need to understand thoroughly the process of breaching. Indeed, from a risk management perspective it is particularly important to have a detailed understanding of the mechanisms (e.g. internal erosion, overtopping erosion) underlying the formation of breaches due to overtopping and reliable information on flows passing through them. Conversely, the current knowledge of breaching mechanisms remains fragmented, especially because dike failure involves complex interactions between flows, materials of the structure, soil and foundations. The existing studies have addressed partially these interactions as the considered idealized dikes were generally homogenous, the piping erosion unaccounted for and the overtopping replicated in a dam-break like configuration. Yet, river embankments are subjected to high flow velocities parallel to the direction of the dike and to flow in the floodplain, which highly influence the shape of the breach and its evolution. The objective of the present work is to fill this gap. A laboratory experimental investigation is planned in the National Laboratory for Hydraulics and Environment (LNHE) of EDF R&D (France) and in the research group Hydraulics in Environmental and Civil Engineering (HECE) of the University of Liege (Belgium), reproducing realistic configurations of river dikes, accounting for the tangential flow in both main channel and floodplain. It enables thus the assessment of, on the one hand, the effect of the increase of the water level, and on the other hand, the influence of waves. The laboratory tests also consider the effect of a surface layer and composition of the dike core by testing different material mixtures. Geometry and composition of the idealized dikes are representative of typical field dikes, based on the similarity theory. [less ▲]

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