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See detailAn enhanced version of a bone remodelling model based on the continuum damage mechanics theory.
Mengoni, Marlène ULg; Ponthot, Jean-Philippe ULg

in Computer Methods in Biomechanics & Biomedical Engineering (2015), 18(12), 1367-1376

The purpose of this work is to propose an enhancement of Doblaré and García's internal bone remodelling model based on the continuum damage mechanics theory. In their paper, they stated that the evolution ... [more ▼]

The purpose of this work is to propose an enhancement of Doblaré and García's internal bone remodelling model based on the continuum damage mechanics theory. In their paper, they stated that the evolution of the internal variables of the bone microstructure, and its incidence on the modification of the elastic constitutive parameters, may be formulated following the principles of Continuum Damage Mechanics, although no actual damage was considered. The resorption and apposition criteria (similar to the damage criterion) were expressed in terms of a mechanical stimulus. However, the resorption criterion is lacking a dimensional consistency with the remodelling rate. We here propose an enhancement to this resorption criterion, insuring the dimensional consistency while retaining the physical properties of the original remodelling model. We then analyse the change in the resorption criterion hypersurface in the stress space for a 2D analysis. We finally apply the new formulation to analyse the structural evolution of a 2D femur. This analysis gives results consistent with the original model but with a faster and more stable convergence rate. [less ▲]

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See detailBifacial serrated technology in the southern African Still Bay: new data from Sibudu Cave, Kwazulu-Natal
Schmid, Viola; Porraz, Guillaume; Rots, Veerle ULg et al

Conference (2015, September)

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See detailThe materiality of Intangible Cultural Heritage: food and social encounters.
Mescoli, Elsa ULg

Conference (2015, September)

Following the patrimonialization process of the Mediterranean diet, some gastronomies found themselves involved within a common framework of food traditions. Some regional practices, indicated as ... [more ▼]

Following the patrimonialization process of the Mediterranean diet, some gastronomies found themselves involved within a common framework of food traditions. Some regional practices, indicated as representative of national food cultures, were chosen to illustrate a shared heritage that historically took a shape around the Mediterranean sea. This heritage, still concretely performed, needed to be stated and preserved against the globalization of food practices. Institutional and political dynamics, occurring on a transnational level, triggered this process, which is nevertheless not detached from the communities involved. Common people played a fundamental role not only in promoting the patrimonialization process itself, but above all in concretely perpetuating some traditions and in spreading them in the contemporary world. In particular, some different cultural groups that found themselves living a common territory and social context thanks to migration, began dialoguing about their own food traditions, starting from some shared elements. As a consequence, some gastronomies interact through people’s practices and define in relation one to the other. This is the case, among others, of Moroccan and Italian cuisine. Throughout a doctoral research conducted within a group of Moroccan women living in the North of Italy, I collected an amount of ethnographic materials showing how social encounters developed through food. The influence of the patrimonialization process on these encounters made people try to find similarities among different traditional practices or to describe some ways of reinterpreting them in reason of the new context. My presentation will focus on these dynamics, thus proving that the Intangible Cultural Heritage is indeed grounded on materiality, that is, in this case, the concrete performance of food practices and their pragmatic effects on relations among humans. [less ▲]

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See detailNonlinear Background Filter to Improve Pedestrian Detection
Wang, Yi; Pierard, Sébastien ULg; Su, Song-Zhi et al

in International Conference on Image Analysis and Processing (ICIAP) (2015, September)

In this paper, we propose a simple nonlinear filter which improves the detection of pedestrians walking in a video. We do so by first cumulating temporal gradient of moving objects into a motion history ... [more ▼]

In this paper, we propose a simple nonlinear filter which improves the detection of pedestrians walking in a video. We do so by first cumulating temporal gradient of moving objects into a motion history image (MHI). Then we apply to each frame of the video a motion-guided nonlinear filter whose goal is to smudge out background details while leaving untouched foreground moving objects. The resulting blurry-background image is then fed to a pedestrian detector. Experiments reveal that for a given miss rate, our motion-guided nonlinear filter can decrease the number of false positives per image (FPPI) by a factor of up to 26. Our method is simple, computationally light, and can be applied on a variety of videos to improve the performances of almost any kind of pedestrian detectors. [less ▲]

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See detailExploring the schizophrenic hyperreflexivity on the Rorschach test
Englebert, Jérôme ULg; Bataille, Jennifer; Mormont, Christian ULg et al

Poster (2015, August 28)

L’hyper-réflexivité schizophrénique peut être définie comme une attitude particulière de la conscience consistant à interroger de façon explicite et réflexive des phénomènes généralement implicites et ... [more ▼]

L’hyper-réflexivité schizophrénique peut être définie comme une attitude particulière de la conscience consistant à interroger de façon explicite et réflexive des phénomènes généralement implicites et préréflexifs (Sass, 2014). Notre hypothèse est que ce mécanisme se manifeste dans les protocoles du test de Rorschach des sujets schizophrènes (Englebert, 2013). Pour l’éprouver, nous avons administré le test à douze sujets schizophrènes. L’originalité de cette recherche repose sur une seconde présentation des planches (trois jours plus tard) qui a permis d’évoquer avec les sujets la permanence de leurs perceptions et de discuter de l’acception commune de celles-ci (pensez-vous que la plupart des autres personnes pourrait voir ce que vous voyez ?). Les résultats confirment notre hypothèse, tant au niveau quantitatif (les marqueurs de l’hyper-réflexivité que nous avions identifiés se retrouvent dans la majorité des protocoles) que qualitatif (phrases suggérant une interrogation épistémologique du test, par exemple). Enfin, nous remarquerons que l’attitude schizophrénique envers le test de Rorschach est assez subtile puisqu’elle identifie le fondement épistémologique du test reposant sur la nécessité d’une fausse perception – une « violation de la réalité » selon Exner (2003). Les sujets schizophrènes mettent en évidence la règle implicite sur laquelle repose le test qui consiste à ne pas donner la seule véritable bonne réponse (systématique) au test qui est « une tache ». [less ▲]

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See detailA Rorschach study of the borderline personality
Englebert, Jérôme ULg; Rommes, Jennifer; Mormont, Christian ULg et al

Conference (2015, August 28)

Nous étudions les manifestations psychologiques au test de Rorschach de sujets présentant un diagnostic de trouble de la personnalité borderline. Dans la continuité des études de Mormont (1969) et Mihura ... [more ▼]

Nous étudions les manifestations psychologiques au test de Rorschach de sujets présentant un diagnostic de trouble de la personnalité borderline. Dans la continuité des études de Mormont (1969) et Mihura (2006), nous avons administré le test à 15 sujets selon les recommandations du Système Intégré. Nos résultats indiquent les tendances spécifiques suivantes : une affectivité qui tend à être extratensive ou ambiéquale (86,7% des sujets), une proportion élevée de réponses couleur/forme (80%), un nombre élevé d’abstractions (66,7%), un nombre important de réponses « agressives » (80%) et « morbides » (86,7%). Une altération variable du testing de la réalité apparait pour chaque protocole. Notons la présence importante (80%) de références personnelles (PER). Signalons également la présence constante de termes particuliers dans le verbatim : énonciation de la couleur rouge (sang, amour), caractère dysphorique de certaines réponses (monstrueux, diabolique), ainsi que des perceptions duales (le bien/le mal). En conclusion, notre étude suggère que le Rorschach en Système Intégré, repérant en première approche des éléments psychologiques que l'on peut raisonnablement mettre en rapport avec la sémiologie clinique et la théorie des personnalités borderlines, l'approfondissement de la recherche peut laisser espérer une meilleure compréhension de ce trouble complexe. [less ▲]

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See detailThe Rorschach and the theory of art: the sublime and the formal
Englebert, Jérôme ULg; Sass, Louis

Conference (2015, August 28)

Together with the crucial work of standardization initiated by Exner, a future focus for research on the Rorschach test concerns the psychological significance of the variables. The Comprehensive System ... [more ▼]

Together with the crucial work of standardization initiated by Exner, a future focus for research on the Rorschach test concerns the psychological significance of the variables. The Comprehensive System has a solid empirical basis offering impressive validity and reliability. By contrast, study and discussion of the psychological correlates of the different codes and their interpretation remains something of a work-in-progress, in much need of both speculative hypotheses and theoretical reflection. In this context, we hope to offer an original hypothesis that is rooted in esthetic theory (Schiller, Burke, Schopenhauer), literature (Stendahl), the philosophy of art (Kant), and existential philosophy (Heidegger). In this paper we propose to introduce the notion of the « sublime », which is to be distinguished from the « beautiful », in order to provide a way of interpreting the significance of both Vista (V) and Form Dimension (FD) responses in the Rorschach. The sublime is associated with a submersion of the cognitive faculties, even a state of feeling overwhelmed, in contrast with the clarity of the beautiful, which is associated with an experience of things being circumscribed in space and under the cognitive/perceptual control of the subject. Our reflection will lead into discussion of the links between perception and anxiety, and to the distinction to be made between anxiety and fear. In concluding, we will take up the adaptive dimension of Vista and FD responses, insofar as they reflect, in accord with Rorschach (1921) and Exner (2003), various forms of introspective awareness. [less ▲]

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See detailChallenges for the restoration of dry calcareous grasslands in quarries: does nature need help?
Pitz, Carline ULg; Piqueray, Julien; Harzé, Mélanie ULg et al

Conference (2015, August 26)

In order to maximize the biodiversity potential of dry calcareous grasslands in former quarries two options are available to managers: (i) allow species to spontaneously recolonize the site, (ii ... [more ▼]

In order to maximize the biodiversity potential of dry calcareous grasslands in former quarries two options are available to managers: (i) allow species to spontaneously recolonize the site, (ii) implement technical support for ecosystem restoration. This study aimed at characterizing the spontaneous communities established in dry area of unexploited quarries and at comparing communities encountered to the succession panel of dry grasslands. To evaluate the ecological succession in quarries, three successional stages where defined: (i) less than three years; (ii) three to 20 years; and (iii) more than 20 years after exploitation. For each successional stage, six parcels were selected and 20 1m2 plots were randomly marked in each parcel. All selected parcels presented dry grasslands abiotic conditions: filtering and stony soils and south orientation. During the 2014 vegetation period, percentage cover of higher plant species was recorded in each plot. Explaining environmental variables including coordinates, altitude, slope (degrees), soil depth, exposure, maximum vegetation height, bare ground cover, moss cover, and shrub cover (%) were measured. Our main results showed that, over decades of time, the ecological succession in dry area of unexploited quarries does not approach a typical formation of dry calcareous grassland. Most recolonizations tended to form meadows communities, except for three sites belonging to a specific landscape context. Potential implications for future quarries restoration will be discussed. [less ▲]

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See detailNegative Relative Clauses in Late Egyptian. A Functional Perspective
Sojic, Nathalie ULg

Poster (2015, August 26)

The poster contains a functional taxonomy of the negative relative clauses in Late Egyptian

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See detailUSING OF AN EXPERIMENTAL DESIGN TO CHARACTERIZE THE CONVECTIVE DRYING BEHAVIOR OF DIFFERENT SLUDGES
Fraikin, Laurent ULg; Salmon, Thierry ULg; Herbreteau, Benjamin et al

in Drying Technology (2015, August 18), 33(11), 1302-1308

Drying appears as a major step prior to valorization of sludge from wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to ... [more ▼]

Drying appears as a major step prior to valorization of sludge from wastewater treatment plant. This study uses an experimental design on different sludges to highlight the drying behavior according to drying conditions, storage and extrusion. This research is performed with industrial view, but on a single cylinder sample, and focuses on five responds: maximum drying flux, time to reach 95% of dry matter, final volume, critical moisture and slowing-down coefficient. [less ▲]

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See detailBiotechnological potential of novel bacterial strains isolated on the brown alga Ascophyllum nodosum
Martin, Marjolaine ULg; Martin, Renée ULg; Barbeyron, Tristan et al

Conference (2015, August 18)

Bacteria associated with algae are underexplored despite their huge biodiversity and the fact that they differ markedly from those living freely in seawater. These bacterial communities are known to ... [more ▼]

Bacteria associated with algae are underexplored despite their huge biodiversity and the fact that they differ markedly from those living freely in seawater. These bacterial communities are known to represent great potential for the production of diverse bioactive compounds, such as specific glycoside hydrolases, as they interact in multiple complex ways with their host. Furthermore, enzymes from marine bacteria have original properties, like cold-adapted, halotolerant and highly stable, which are constantly searched out by bio-industries. The aim of our study was to identify bacteria, associated with the brown alga Ascophyllum nodosum, showing diverse polysaccharolytic activities. To isolate cultivable microorganisms, algal thalli of Ascophyllum nodosum were swabbed with sterile cotton tips and marine agar plates were inoculated. Three-hundred isolated bacteria were screened for agarase, kappa- and iota-carrageenase, and sulfatase activities on specific marine media. Thirty-two bacteria with polysaccharolytic activities were isolated and a part of their 16S rDNA (8F-1492R) were amplified and sequenced. Twenty-seven were classified as Flavobacteriia and five as Gammaproteobacteria. Putative new strains and species of Zobellia, Maribacter, Cellulophaga, Shewanella, Glaciecola, Pseudoalteromonas and Colwellia were identified by phylogenetic analysis. All those genera are well-known to colonize algal surface but only some of them are famous to degrade algal polysaccharides (Zobellia, Maribacter, Cellulophaga, and Pseudoalteromonas). However, all those novel bacterial strains/species showed multiple and diverse enzymatic activities (agarase, iota-and kappa-carrageenase, cellulase, beta-glucosidase, sulfatase and/or amylase activities). Genomics libraries with their DNA were constructed in Escherichia coli and Bacillus subtilis and are screened to identify the genes coding for the observed enzymatic activities. Those novel glycoside hydrolases from unknown marine bacteria should have original and innovative properties with great biotechnological potential. [less ▲]

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See detailAGING MECHANISMS IN AMORPHOUS PHASE CHANGE MATERIALS
Raty, Jean-Yves ULg

Conference (2015, August 18)

Aging phenomena are common to all amorphous structures, but of special importance in phase change materials (PCM) since it impedes the realization of multi-level memories. Different interpretations have ... [more ▼]

Aging phenomena are common to all amorphous structures, but of special importance in phase change materials (PCM) since it impedes the realization of multi-level memories. Different interpretations have been proposed, but we focus here on the structural relaxation of amorphous GeTe, chosen because it is the simplest system that is representative of the wider class of GST alloys, lying along the GeTe-Sb2Te3 composition line of the GeSbTe phase diagram. The direct melt-and-quench DFT based Molecular Dynamics approach leads to models with a few hundred atoms, and, hence a small number of atomic environments. Here we sample a large number of local atomic environments, and bonding schemes, by chemically substituting different alloys to favor different local atomic structures. This enables spanning a larger fraction of the configuration space relevant to aging. GST alloys are known to display complex bonding that does not follow the chemist’s “octet-rule”. This lead to many controversies, especially concerning the local structure around Ge atoms. We overcome this problem by using state of the art non local DFT-MD, including the so-called van der Waals corrections. This leads to more clearly defined environments that are thoroughly analyzed. We can then identify their fingerprints in the available structural experimental data and assess their stability to find the driving forces leading to the structural relaxation. The calculated electronic properties nicely match the most recent photothermal deflection spectroscopy experiments. Our results support a model of the amorphous phase and its time evolution that involves an evolution of the local (chemical) order towards that of the crystal (by getting rid of homopolar bonds), and an evolution of its electronic properties that drift away from those of the crystal, driven by an increase of the Peierls-like distortion of the local environments in the amorphous [1]. [1] J.Y Raty, W. Zhang, J. Luckas, C. Chen, R. Mazzarello, C. Bichara and M. Wuttig, Nature Comm. To appear. [less ▲]

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See detailAtmospheric metal pollution over the last 250 years inferred from speleothem geochemistry
Allan, Mohammed ULg; Fagel, Nathalie ULg; verheyden, sophie

Conference (2015, August 17)

Lead concentrations and isotope ratios from two speleothems from the Han-sur-Lesse cave in southern Belgium were measured in order to study the ability of speleothems to act as archives of atmospheric ... [more ▼]

Lead concentrations and isotope ratios from two speleothems from the Han-sur-Lesse cave in southern Belgium were measured in order to study the ability of speleothems to act as archives of atmospheric pollution. To address this aim we analyzed trace elemental Al and Pb compositions by LA-ICP-MS and ICP-MS as well as Pb isotopes by MC-ICP-MS. The results help to identify three Pb-enriched intervals: from 1880 to 1905 AD, from 1945 to 1965 AD, and from 1975 to 1990 AD. The speleothem record is consistent with the evolution of atmospheric pollution in Belgium. Lead isotope ratios confirm that coal and gasoline combustion, combined with regional metallurgical activities, were the predominant Pb pollution sources in the stalagmites during the last 250 years. This research underscores the importance of speleothems as a valuable tool for the discrimination between anthropogenic and natural lead contributions in the environment and consequently for quantifying the anthropogenic contribution or determining natural background values in continental settings. [less ▲]

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See detailJouer avec les mots, pourquoi et comment ?
Rigo, Michel ULg

Scientific conference (2015, August 04)

A l'instar de Raymond Queneau et ses cent mille milliards de poèmes, cet exposé a pour but de compter et de construire des mots aux propriétés parfois surprenantes. Les premiers résultats en combinatoire ... [more ▼]

A l'instar de Raymond Queneau et ses cent mille milliards de poèmes, cet exposé a pour but de compter et de construire des mots aux propriétés parfois surprenantes. Les premiers résultats en combinatoire des mots remontent au début du siècle précédent, avec les travaux du mathématicien norvégien Axel Thue. Cette branche des mathématiques étudie la structure et les arrangements apparaissant au sein de suites finies, ou infinies, de symboles appartenant à un ensemble fini. Donnons un exemple rudimentaire. Un carré est la juxtaposition de deux répétitions d'un mot, ainsi "coco" ou "bonbon" sont des carrés. On dira alors qu'un mot comme "taratata" contient un carré. Il est aisé de vérifier que, si on dispose uniquement de deux symboles "a" et "b", alors tout mot de longueur au moins 4 contient un des carrés "aa", "bb", "abab" ou encore "baba". On dira donc que, sur deux symboles, les carrés sont inévitables. Cette observation pose des questions intéressantes et simples à formuler : Avec trois symboles, peut-on construire un mot arbitrairement long ne contenant pas de carré ? Si on se limite à deux symboles, peut-on construire un mot arbitrairement long sans cube, i.e., évitant la juxtaposition de trois répétitions d'un même mot ? En fonction de la taille de l'alphabet, quels motifs doivent nécessairement apparaître et quels sont ceux qui sont évitables ? Que se passe-t-il si on autorise certaines permutations ? etc. Dans cet exposé, on passera en revue quelques constructions simples de mots finis ou infinis : mot de Thue-Morse, mot de Fibonacci, mots Sturmiens. Nous montrerons aussi que les applications sont nombreuses : arithmétique, transcendance en théorie des nombres, informatique mathématique et théorie des automates, pavages du plan, dynamique symbolique et codage de rotations, infographie, géométrie discrète et représentation de segment de droites à l'écran, bio-informatique, ... [less ▲]

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See detailTime series of high-resolution spectra of SN 2014J observed with the TIGRE telescope
Jack, D.; Mittag, M.; Schröder, K.-P. et al

in Monthly Notices of the Royal Astronomical Society (2015), 451

We present a time series of high-resolution spectra of the Type Ia supernova 2014J, which exploded in the nearby galaxy M82. The spectra were obtained with the HEROS échelle spectrograph installed at the ... [more ▼]

We present a time series of high-resolution spectra of the Type Ia supernova 2014J, which exploded in the nearby galaxy M82. The spectra were obtained with the HEROS échelle spectrograph installed at the 1.2-m TIGRE telescope. We present a series of 33 spectra with a resolution of R ≈ 20 000, which covers the important bright phases in the evolution of SN 2014J during the period from 2014 January 24 to April 1. The spectral evolution of SN 2014J is derived empirically. The expansion velocities of the Si II P-Cygni features were measured and show the expected decreasing behaviour, beginning with a high velocity of 14 000 km s[SUP]-1[/SUP] on January 24. The Ca II infrared triplet feature shows a high-velocity component with expansion velocities of >20 000 km s[SUP]-1[/SUP] during the early evolution apart from the normal component showing similar velocities as Si II. Further broad P-Cygni profiles are exhibited by the principal lines of Ca II, Mg II and Fe II. The TIGRE SN 2014J spectra also resolve several very sharp Na I D doublet absorption components. Our analysis suggests interesting substructures in the interstellar medium of the host galaxy M82, as well as in our Milky Way, confirming other work on this SN. We were able to identify the interstellar absorption of M82 in the lines of Ca II H & K at 3933 and 3968 Å as well as K I at 7664 and 7698 Å. Furthermore, we confirm several diffuse interstellar bands, at wavelengths of 6196, 6283, 6376, 6379and 6613 Å and give their measured equivalent widths. [less ▲]

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See detailA force sensor based on three weakly coupled resonators with ultrahigh sensitivity
Zhao, Chun; Wood, Graham; Xie, J.B. et al

in Sensors and Actuators. A, Physical (2015), 232

A proof-of-concept force sensor based on three degree-of-freedom (DoF) weakly coupled resonatorswas fabricated using a silicon-on-insulator (SOI) process and electrically tested in 20 Torr vacuum.Compared ... [more ▼]

A proof-of-concept force sensor based on three degree-of-freedom (DoF) weakly coupled resonatorswas fabricated using a silicon-on-insulator (SOI) process and electrically tested in 20 Torr vacuum.Compared to the conventional single resonator force sensor with frequency shift as output, by measuringthe amplitude ratio of two of the three resonators, the measured force sensitivity of the 3DoF sensor was4.9 × 106/N, which was improved by two orders magnitude. A bias stiffness perturbation was applied toavoid mode aliasing effect and improve the linearity of the sensor. The noise floor of the amplitude ratiooutput of the sensor was theoretically analyzed for the first time, using the transfer function model ofthe 3DoF weakly coupled resonator system. It was shown based on measurement results that the outputnoise was mainly due to the thermal–electrical noise of the interface electronics. The output noise spectraldensity was measured, and agreed well with theoretical estimations. The noise floor of the force sensoroutput was estimated to be approximately 1.39nN for an assumed 10 Hz bandwidth of the output signal,resulting in a dynamic range of 74.8 dB. [less ▲]

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See detailOptical study of diffraction grating/Fresnel lens combinations applied to a spectral-splitting solar concentrator for space applications
Michel, Céline ULg; Loicq, Jerôme ULg; Thibert, Tanguy ULg et al

in Applied Optics (2015), 54(22), 6666-6673

This paper presents a new design of a planar solar concentrator with spectral splitting of light for space applications. This concentrator spectrally splits the incident light into mainly two parts. Each ... [more ▼]

This paper presents a new design of a planar solar concentrator with spectral splitting of light for space applications. This concentrator spectrally splits the incident light into mainly two parts. Each part is then focused onto specific spatially separated photovoltaic cells, allowing for independent control of respective cells output power. These advantages of both spectral splitting and light focusing are here combined thanks to a specific diffraction grating superimposed on a Fresnel lens. The theoretical principle of the optical design is presented, with optimization of each element and improvement steps, including optimization of grating period evolution along the lens, and testing of two kinds of gratings (a blazed and a lamellar one). First numerical results are presented, highlighting the possibility to design a concentrator at about 10× or more for each cell, with an output power larger than that of a classical concentrator focusing on a GaAs SJ cell, and less than 10% of losses for tracking errors up to ±0.8°. Some experimental results are also presented. [less ▲]

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See detailThe Airline Container Loading Problem with Pickup and Delivery
Lurkin, Virginie ULg; Schyns, Michael ULg

in European Journal of Operational Research (2015), 244(3), 955-965

This paper considers the loading optimization problem for a set of containers and pallets transported into a cargo aircraft that serves multiple airports. Because of pickup and delivery operations that ... [more ▼]

This paper considers the loading optimization problem for a set of containers and pallets transported into a cargo aircraft that serves multiple airports. Because of pickup and delivery operations that occur at intermediate airports, this problem is simultaneously a Weight & Balance Problem and a Sequencing Problem. Our objective is to minimize fuel and handling operation costs. This problem is shown to be NP-hard. We resort to a mixed integer linear program. Based on real-world data from a professional partner (TNT Airways), we perform numerical experiments using a standard B&C library. This approach yields better solutions than traditional manual planning, which results in substantial cost savings. [less ▲]

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See detailIsolation and identification of anthropogenic particles in fish stomachs by Raman spectroscopy: a new method
Collard, France ULg; Gilbert, Bernard ULg; Eppe, Gauthier ULg et al

in Organohalogen Compounds (2015, August)

Microplastic particles (MP) contaminate oceans and affect marine organisms in several ways. Ingestion combined with food intake is generally reported. However, data interpretation is often circumvented by ... [more ▼]

Microplastic particles (MP) contaminate oceans and affect marine organisms in several ways. Ingestion combined with food intake is generally reported. However, data interpretation is often circumvented by the difficulty to separate MP from bulk samples. Visual examination is often used as one or the only step to sort these particles. However, color, size and shape are insufficient and often unreliable criteria. Here we present an isolation method of MP specially adapted to a subsequent analysis by Raman spectroscopy. This method avoids fluorescence problems allowing the identification anthropogenic particles (AP) from stomach contents of fish by Raman spectroscopy. It was validated with commercial samples of microplastics and cotton along with stomach contents from three different Clupeiformes fishes: Clupea harengus, Sardina pilchardus and Engraulis encrasicolus. The optimized digestion and isolation protocol showed no visible impact on microplastics and cotton particles while the spectroscopic analysis allowed precise identification of microplastics and textile fibers. This approach allowed us to isolate 35 particles. These were analyzed by Raman spectroscopy: eleven were microplastics and thirteen were made of cellulose or lignin, or both (mostly fibers). Some particles were not identified but contained artificial colorants. This isolation protocol will help to assess the presence, quantity and composition of AP in planktivorous fish stomachs. [less ▲]

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