Last 7 days
Bookmark and Share    
Full Text
See detailA geometric local frame approach for flexible multibody systems
Sonneville, Valentin ULg

Doctoral thesis (2015)

The notion of frame is ubiquitous in the kinematic description of flexible multibody models. In this work, a differential-geometric framework is selected to describe frame operations in a rigorous and ... [more ▼]

The notion of frame is ubiquitous in the kinematic description of flexible multibody models. In this work, a differential-geometric framework is selected to describe frame operations in a rigorous and systematic way. A frame transformation is thus seen as an element of the special Euclidean group $SE(3)$, which is represented by a four by four transformation matrix, and frame operations, such as spatial interpolation or time integration, rely on non-linear but analytical expressions in which translation and rotation contributions are inherently coupled. Based on this formalism, this thesis develops geometrically exact formulations of many classical components used in flexible multibody system modelling, which includes the formulation of a rigid body, several kinematic joints, a flexible beam, a flexible shell and a superelement. As opposed to most popular techniques in the literature, a local frame representation of the equations of motion is adopted in this work. This means that the unknown kinematic variables such as the motion increments, the velocities and the accelerations, as well as the generalized forces are all expressed in a local frame attached to the body. After spatial semi-discretization, the equations of motion of a multibody system take the form of differential-algebraic equations on a Lie group which can be conveniently solved in a global parametrization-free approach using a Lie group integration scheme. This thesis presents numerous arguments to recommend this framework for the development of efficient codes for the numerical simulation of flexible multibody systems. On the one hand, the proposed framework leads to novel and interesting theoretical aspects. For instance, it features a naturally singularity-free description of large rotations and it leads to inherently shear-locking free beam and shell finite elements. On the other hand, the formulation leads to unprecedented computational properties. The geometric non-linearities are naturally filtered out of the equilibrium equations such that non-linearities are significantly reduced, as compared to classical formulations. In particular, the iteration matrix, which is used in implicit integration schemes, is insensitive to overall large amplitude motions and is only affected by local relative transformations, such as deformations in flexible elements and relative motions in kinematic joints. This property can be exploited to strongly reduce computational costs, as compared to classical formulations. [less ▲]

Detailed reference viewed: 58 (14 ULg)
Full Text
See detailPer una misura del ritorno: Nievo nel Quarantotto di Sciascia
Curreri, Luciano ULg

Learning material (2015)

Detailed reference viewed: 54 (1 ULg)
Full Text
See detailExperimental study and modeling of the quasi-static mechanical behavior of Ti6Al4V at room temperature
Gilles, Gaëtan ULg

Doctoral thesis (2015)

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts ... [more ▼]

The work aims to characterize the quasi-static mechanical behavior of the Ti6Al4V titanium alloy at room temperature and to describe it by a phenomenological model. The thesis is divided in four parts. The first one presents a literature review of the basic properties of titanium and its alloys (crystal structure, classification, deformation mechanisms), then it focuses on the specific mechanical features of Ti6Al4V. It also proposes a state of art in the field of the phenomenological constitutive laws used to model the mechanical behaviors of metals. The second part deals with the experimental campaign conducted on a 0.6 mm thick Ti6Al4V sheet. The devices and the tests are first described before giving the test results. The campaign includes experiments with monotonic and complex strain paths (tension, compression, simple shear, plane strain, Bauschinger tests, deep-drawing processes, layer compression tests). The experimental results show that the material displays anisotropy in yield stress, r-ratios and hardening, as well as a strength differential effect between tension and compression. The third part describes the implementation of the yield criteria CPB06exn in the non-linear finite element code LAGAMINE developed in MSM team. These criteria are selected to model the yield locus of Ti6Al4V since they are able to take into account both the anisotropy and the tension-compression asymmetry exhibited by the alloy. Several parameter identifications are performed using the classical simulated annealing algorithm. They determine that CPB06ex2 is required to represent the yield surface. The criterion is next associated to different hardening formulations: (1) Voce isotropic law; (2) mixed Voce isotropic – Armstrong-Frederick kinematic law; (3) model taking into account the evolution of the yield locus shape with the deformation. The identification of the hardening parameters is achieved from the monotonic and Bauschinger tests either by inverse method, or by the simulated annealing method. The last part of the thesis proposed a validation of the different modelings in the case of the layer compression tests and the deep-drawing processes. [less ▲]

Detailed reference viewed: 70 (11 ULg)
Full Text
Peer Reviewed
See detailEpidemiology and clinical reporting of candidaemia in Belgium : a national prospective study (TANSIR trial)
Trouvé, Charlotte; Blot, Stijn; Hayette, Marie-Pierre ULg et al

Poster (2015, April 26)

Detailed reference viewed: 19 (0 ULg)
Full Text
Peer Reviewed
See detailVertical Distribution of Functional Potential and Active Microbial Communities in Meromictic Lake Kivu
İnceoğlu, Özgul; Llirós, Marc; Crowe, Sean A. et al

in Microbial Ecology (2015)

Detailed reference viewed: 10 (0 ULg)
Full Text
See detailLes méthodes de prise en charge et de rééducation cognitives
DELRUE, Gaël ULg

Conference (2015, April 25)

Présentation des méthodes de prise en charge neurocognitives de patients traumatisés crâniens légers.

Detailed reference viewed: 22 (0 ULg)
Full Text
Peer Reviewed
See detailAge at Retirement: New Proxy of Cognitive Reserve? Results from a French Population-Based Study
Grotz, Catherine ULg; Meillon, Céline; Amieva, Hélène et al

Conference (2015, April 25)

Detailed reference viewed: 27 (4 ULg)
Full Text
Peer Reviewed
See detailEffect of nanocrystalline structure on magnetocaloric effect in manganite composites (1/3)La0.7Ca0.3MnO3/(2/3)La0.8Sr0.2MnO3
Pękała, M; Pękała, K; Drozd, V et al

in Journal of Alloys & Compounds (2015), 629

Detailed reference viewed: 28 (3 ULg)
See detailHenri Pirenne à Liège ou l'ambition (1878-1885). La genèse d’un réseau académique et politique
Genin, Vincent ULg

Conference given outside the academic context (2015)

Detailed reference viewed: 12 (0 ULg)
See detailWerner Herzog et Alexander Kluge. Regards croisés sur le Nouveau Cinéma Allemand.
Hamers, Jérémy ULg

Conference (2015, April 25)

Alexander Kluge et Werner Herzog sont assurément deux figures antipodiques dans l’histoire du cinéma allemand. L’engagement politique tout d’abord, indissociable de la création audiovisuelle pour le ... [more ▼]

Alexander Kluge et Werner Herzog sont assurément deux figures antipodiques dans l’histoire du cinéma allemand. L’engagement politique tout d’abord, indissociable de la création audiovisuelle pour le premier, objet de méfiance si pas de rejet pour le second, oppose manifestement ces deux figures de proue du Nouveau Cinéma Allemand, un courant dont l’acte de naissance, le manifeste d’Oberhausen de 1962, coïncide avec les débuts cinématographiques des deux auteurs. Leurs esthétiques respectives ensuite confirment le gouffre irréductible qui semble les séparer. Enfin, auteurs l’un et l’autre d’œuvres théoriques sur le cinéma, ils défendent deux approches réflexives de la création audiovisuelle qui apparaissent a priori comme inconciliables. En première lecture, Kluge et Herzog incarnent donc toute l’hétérogénéité bien connue du Nouveau Cinéma Allemand. À rebours de ce constat largement répandu dans les histoires de ce courant cinématographique, et sans pour autant réconcilier les deux auteurs à tout prix, un regard croisé sur quelques-uns de leurs films (e.a. Gelegenheitsarbeit einer Sklavin et Die Artisten in der Zirkuskuppel : ratlos pour Kluge ; Fata Morgana et Fitzcarraldo pour Herzog) et textes (e.a. les écrits d’Ulm de Kluge et la déclaration du Minnesota de Herzog) permet de dégager plusieurs points de rencontre entre les œuvres des deux cinéastes. Partant plus particulièrement de leurs conceptions de la rencontre entre documentaire et fiction, rencontre essentielle pour l’un comme pour l’autre, il s’agira d’en dégager les similitudes et résonances pour mieux comprendre, grâce à un éclairage réciproque, l’une et l’autre de ces œuvres essentielles du cinéma allemand des années soixante, septante et quatre-vingt. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
Peer Reviewed
See detailEvaluation of a commercially developed semi-automated PCR-surface enhanced raman scattering assay for the detection of Candida species in blood
HAYETTE, Marie-Pierre ULg; WERY, Marie ULg; BOREUX, Raphaël ULg et al

Poster (2015, April 25)

Objectives Microbiological diagnosis of invasive candidiasis is still dependent on culture-based methods. The use of beta-D-glucan antigen detection is included in the EORTC microbiological diagnostic ... [more ▼]

Objectives Microbiological diagnosis of invasive candidiasis is still dependent on culture-based methods. The use of beta-D-glucan antigen detection is included in the EORTC microbiological diagnostic criteria but is rarely available in the clinical labs. On the other hand, PCR-based methods lack standardization. The RenDx Fungiplex® is a new commercially available semi-automated PCR SERS assay designed for the detection of Aspergillus sp. and Candida sp. including the differentiation of resistant strains as C. glabrata, C. krusei and A. terreus. This study was performed for sensitivity and reproducibility testing of the method on 8 different Candida species. Methods The study was conducted on EDTA-blood collected from a healthy donor. Blood samples were spiked with 10 Candida reference strains: C. albicans ATCC 10231, C. albicans NEQAS 1206 and C. albicans NEQAS 2359; C. glabrata ATCC 90030 ; C. krusei ATCC 6258 ; C. tropicalis NEQAS 1036 ; C. guillermondii NEQAS 1035 ; C. parapsilosis ATCC 22019 ; C. lusitaniae NEQAS 1511 and C. dubliniensis IHEM 14280. Spiked samples were diluted at final concentrations ranging from 1 CFU/mL to 1000 CFU/mL. Cultures on Sabouraud dextrose agar were performed in parallel to control yeasts dilutions. DNA extraction was performed by using proteinase K-based method followed by purification on QIAcube automate. The RenDx Fungiplex®kit (Renishaw) was used for the amplification process and the final detection was processed on the SP-1000 sample analyzer. Reproducibility testing was performed on the three C. albicans reference strains by repeating each test 5 times. Results A total of 142 samples were included in the study. A sensitivity of 10 CFU/mL was reached for C. glabrata, C. krusei, C. tropicalis, C. dubliniensis spiked samples while C. lusitaniae and C. tropicalis performed better at 1 CFU/mL. The three tested reference C. albicans strains and C. guillermondii gave the lowest sensitivity (100 CFU/mL). The reproducibility of the assay was 96% Conclusion RenDx Fungiplex®kit allows the detection of the most frequent Candida species responsible for invasive candidiasis in spiked blood samples. The sensitivity of the test is comprised between 10 and 100 CFU/mL for most Candida sp. and reproducibility is very high. This evaluation allows us to consider this commercial kit for inclusion in a clinical study on invasive candidiasis in comparison with non-molecular diagnostic assays. [less ▲]

Detailed reference viewed: 47 (3 ULg)
See detailLe crime en obsession : "Chien enragé" d'Akira Kurosawa
Tomasovic, Dick ULg

Conference given outside the academic context (2015)

Analyse du film "Chien enragé" d'Akira Kurosawa (1949) et de son contexte de création.

Detailed reference viewed: 8 (0 ULg)
See detailLes appareils idéologiques du Prince. Une lecture de “Machiavel et nous” (Althusser)
Mancuso, Eva ULg

Scientific conference (2015, April 25)

Detailed reference viewed: 15 (0 ULg)
Full Text
Peer Reviewed
See detailTumor suppressive p53 signaling empowers metastatic inhibitor KLF17-dependent transcription to overcome tumorigenesis in non-small cell lung cancer.
Ali, Amjad ULg; Zeeshan Bhatti M; Saboor Shah A et al

in Journal of Biological Chemistry (2015)

Metastasis, which is controlled by concerted action of multiple genes, is a complex process, and is important cause of cancer death. KLF17 is a negative regulator of metastasis and epithelial-mesenchymal ... [more ▼]

Metastasis, which is controlled by concerted action of multiple genes, is a complex process, and is important cause of cancer death. KLF17 is a negative regulator of metastasis and epithelial-mesenchymal-transition (EMT) during cancer progression. However, the underlying molecular mechanism and biological relevance of KLF17 in cancer cells are poorly understood. Here, we show that tumor suppressor protein p53 plays an integral role to induce KLF17 expression in NSCLC. p53 is recruited to KLF17 promoter and results in the formation of p53-DNA complex. p53 enhances binding of p300, and favors histone acetylation on KLF17 promoter. Mechanistically, p53 physically interacts with KLF17 and thereby enhances anti-metastatic function of KLF17. p53 empowers KLF17 mediated EMT genes transcription via enhancing physical association of KLF17 to target gene promoters. Nutlin-3 recruits KLF17 to EMT target gene promoters and results in the formation of KLF17-DNA complex via p53-dependent pathway. p53 depletion abrogates DNA binding affinity of KLF17 to EMT target gene promoters. KLF17 is critical for p53 cellular activities in NSCLC. Importantly, KLF17 enhances p53 transcription to generate a novel positive feedback loop. KLF17 depletion accelerates lungs cancer cells growth in response to chemotherapy. Mechanistically, we found that KLF17 increases tumor suppressor genes p53, p21 and pRB expressions in NSCLC. Functionally, KLF17 required p53 to suppress cancer cell invasion and migration in NSCLC. In sum, our study highlights novel insight into anti-EMT affect of KLF17 via p53-dependent pathway in NSCLC, and KLF17 may be a new therapeutic target in NSCLC with p53 status. [less ▲]

Detailed reference viewed: 10 (2 ULg)
Full Text
Peer Reviewed
See detailREGg is critical for skin carcinogenesis by modulating the Wnt/b-catenin pathway
Lei Li; Yongyan Dang; Jishen Zhang et al

in nature communications (2015)

Here we report that mice deficient for the proteasome activator, REGg, exhibit a marked resistance to TPA (12-O-tetradecanoyl-phorbol-13-acetate)-induced keratinocyte proliferation, epidermal hyperplasia ... [more ▼]

Here we report that mice deficient for the proteasome activator, REGg, exhibit a marked resistance to TPA (12-O-tetradecanoyl-phorbol-13-acetate)-induced keratinocyte proliferation, epidermal hyperplasia and onset of papillomas compared with wild-type counterparts. Interestingly, a massive increase of REGg in skin tissues or cells resulting from TPA induces activation of p38 mitogen-activated protein kinase (MAPK/p38). Blocking p38 MAPK activation prevents REGg elevation in HaCaT cells with TPA treatment. AP-1, the downstream effector of MAPK/p38, directly binds to the REGg promoter and activates its transcription in response to TPA stimulation. Furthermore, we find that REGg activates Wnt/b-catenin signalling by degrading GSK-3b in vitro and in cells, increasing levels of CyclinD1 and c-Myc, the downstream targets of b-catenin. Conversely, MAPK/p38 inactivation or REGg deletion prevents the increase of cyclinD1 and c-Myc by TPA. This study demonstrates that REGg acts in skin tumorigenesis mediating MAPK/p38 activation of the Wnt/b-catenin pathway. [less ▲]

Detailed reference viewed: 10 (4 ULg)
Full Text
Peer Reviewed
See detailDisrupting the wall accumulation of human sperm cells by artificial corrugation
Guidobaldi, H.A.; Jeyaram, Y.; Condat, C.A. et al

in Biomicrofluidics (2015), 9

Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very di erent from that observed in the bulk. Swimming along walls is bene cial for ... [more ▼]

Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very di erent from that observed in the bulk. Swimming along walls is bene cial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells 60 um long, strongly confi ned to 25u m shallow chambers. We investigate the nature of the cell trajectories between the con fining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confi rmed by depth resolved confocal microscopy studies. We show that the introduction of arti cial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an e ffect which we hypothesize may be valuable for micro fluidic applications in biomedicine. [less ▲]

Detailed reference viewed: 21 (5 ULg)
Full Text
See detailLe futur du vieillissement de la population en Wallonie
Delvenne, Pierre ULg

Conference given outside the academic context (2015)

Detailed reference viewed: 13 (0 ULg)