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Computational Sciences Year 2016 Activity Report Bordas, Stéphane Report (2016) Born from a bottom-up initiative of Mathematics, Computer Science, Physics and Computational Engineering, Computational Sciences (CoSc) have contributed to create at UL a positive and symbiotic research ... [more ▼] Born from a bottom-up initiative of Mathematics, Computer Science, Physics and Computational Engineering, Computational Sciences (CoSc) have contributed to create at UL a positive and symbiotic research environment relying on a strong fundamental scientific research core. CoSc will continue to rationalize research efforts across a range of strategic innovation domains by centralizing research and development tools and building upon the existing strengths of the Luxembourgish research and socio-economic landscape. [less ▲] Detailed reference viewed: 63 (4 UL)Overdamped stochastic thermodynamics with multiple reservoirs ; Esposito, Massimiliano in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2016), 94(062148), After establishing stochastic thermodynamics for underdamped Langevin systems in contact with multiple reservoirs, we derive its overdamped limit using timescale separation techniques. The overdamped ... [more ▼] After establishing stochastic thermodynamics for underdamped Langevin systems in contact with multiple reservoirs, we derive its overdamped limit using timescale separation techniques. The overdamped theory is different from the naive theory that one obtains when starting from overdamped Langevin or Fokker-Planck dynamics and only coincides with it in the presence of a single reservoir. The reason is that the coarse-grained fast momentum dynamics reaches a nonequilibrium state, which conducts heat in the presence of multiple reservoirs. The underdamped and overdamped theory are both shown to satisfy fundamental fluctuation theorems. Their predictions for the heat statistics are derived analytically for a Brownian particle on a ring in contact with two reservoirs and subjected to a nonconservative force and are shown to coincide in the long-time limit. [less ▲] Detailed reference viewed: 83 (4 UL)miRNAs in ancient tissue specimens of the Tyrolean Iceman Kreis, Stephanie ; ; et al in Molecular Biology and Evolution (2016) Detailed reference viewed: 76 (4 UL)Avec le bonjour de René Schneider Scuto, Denis Article for general public (2016) Detailed reference viewed: 62 (3 UL)Klaslokalen Binnenstebuiten: Leerkrachten over de veranderende onderwijsleeromgeving doorheen hun carrière (1960-2015) Herman, Frederik ; Article for general public (2016) Welke scholen hebben we nodig voor de 21ste eeuw? Hoe moeten die toekomstige schoolgebouwen eruitzien? Misschien wel als één grote open werkruimte – met zithoeken, labo’s, vergaderlokalen voor groepswerk ... [more ▼] Welke scholen hebben we nodig voor de 21ste eeuw? Hoe moeten die toekomstige schoolgebouwen eruitzien? Misschien wel als één grote open werkruimte – met zithoeken, labo’s, vergaderlokalen voor groepswerk, een immer toegankelijke media- en bibliotheek, enzovoort – waarin leerkrachten en leerlingen vrij kunnen bewegen naar gelang de activiteiten en noden. Zullen de ‘traditionele’ klaslokalen hun bestaansredenen verliezen in deze nieuwe onderwijsleeromgevingen? Het vraagstuk naar innovatieve scholenbouw is verre van nieuw. Inderdaad, eb en vloed kenmerken onze onderwijsgeschiedenis.klaslokalen hun bestaansredenen verliezen in deze nieuwe onderwijsleeromgevingen? Het vraagstuk naar innovatieve scholenbouw is verre van nieuw. Inderdaad, eb en vloed kenmerken onze onderwijsgeschiedenis. [less ▲] Detailed reference viewed: 320 (5 UL)Optimum stochastic modeling for GNSS tropospheric delay estimation in real-time ; Teferle, Felix Norman ; et al in GPS Solutions (2016) In GNSS data processing, the station height, receiver clock and tropospheric delay (ZTD) are highly correlated to each other. Although the zenith hydrostatic delay of the troposphere can be provided with ... [more ▼] In GNSS data processing, the station height, receiver clock and tropospheric delay (ZTD) are highly correlated to each other. Although the zenith hydrostatic delay of the troposphere can be provided with sufficient accuracy, zenith wet delay (ZWD) has to be estimated, which is usually done in a random walk process. Since ZWD temporal variation depends on the water vapor content in the atmosphere, it seems to be reasonable that ZWD constraints in GNSS processing should be geographically and/or time dependent. We propose to take benefit from numerical weather prediction models to define optimum random walk process noise. In the first approach, we used archived VMF1-G data to calculate a grid of yearly and monthly means of the difference of ZWD between two consecutive epochs divided by the root square of the time lapsed, which can be considered as a random walk process noise. Alternatively, we used the Global Forecast System model from National Centres for Environmental Prediction to calculate random walk process noise dynamically in real-time. We performed two representative experimental campaigns with 20 globally distributed International GNSS Service (IGS) stations and compared real-time ZTD estimates with the official ZTD product from the IGS. With both our approaches, we obtained an improvement of up to 10% in accuracy of the ZTD estimates compared to any uniformly fixed random walk process noise applied for all stations. [less ▲] Detailed reference viewed: 89 (1 UL)Nonequilibrium Thermodynamics of Chemical Reaction Networks: Wisdom from Stochastic Thermodynamics Rao, Riccardo ; Esposito, Massimiliano in Physical Review X (2016), 6(4), 041064 We build a rigorous nonequilibrium thermodynamic description for open chemical reaction networks of elementary reactions. Their dynamics is described by deterministic rate equations with mass action ... [more ▼] We build a rigorous nonequilibrium thermodynamic description for open chemical reaction networks of elementary reactions. Their dynamics is described by deterministic rate equations with mass action kinetics. Our most general framework considers open networks driven by time-dependent chemostats. The energy and entropy balances are established and a nonequilibrium Gibbs free energy is introduced. The difference between this latter and its equilibrium form represents the minimal work done by the chemostats to bring the network to its nonequilibrium state. It is minimized in nondriven detailed-balanced networks (i.e., networks that relax to equilibrium states) and has an interesting information-theoretic interpretation. We further show that the entropy production of complex-balanced networks (i.e., networks that relax to special kinds of nonequilibrium steady states) splits into two non-negative contributions: one characterizing the dissipation of the nonequilibrium steady state and the other the transients due to relaxation and driving. Our theory lays the path to study time-dependent energy and information transduction in biochemical networks. [less ▲] Detailed reference viewed: 191 (24 UL)Il nuovo pilastro europeo per i diritti sociali: insidie e opportunità Ratti, Luca Presentation (2016, December 20) Detailed reference viewed: 43 (2 UL)First-principles modeling of molecular crystals: structures and stabilities, temperature and pressure Hoja, Johannes ; ; Tkatchenko, Alexandre in Wiley Interdisciplinary Reviews: Computational Molecular Science (2016) The understanding of the structure, stability, and response properties of molecular crystals at finite temperature and pressure is crucial for the field of crystal engineering and their application. For a ... [more ▼] The understanding of the structure, stability, and response properties of molecular crystals at finite temperature and pressure is crucial for the field of crystal engineering and their application. For a long time, the field of crystal-structure prediction and modeling of molecular crystals has been dominated by classical mechanistic force-field methods. However, due to increasing computational power and the development of more sophisticated quantum-mechanical approximations, first-principles approaches based on density functional theory can now be applied to practically relevant molecular crystals. The broad transferability of first-principles methods is especially imperative for polymorphic molecular crystals. This review highlights the current status of modeling molecular crystals from first principles. We give an overview of current state-of-the-art approaches and discuss in detail the main challenges and necessary approximations. So far, the main focus in this field has been on calculating stabilities and structures without considering thermal contributions. We discuss techniques that allow one to include thermal effects at a first-principles level in the harmonic or quasi-harmonic approximation, and that are already applicable to realistic systems, or will be in the near future. Furthermore, this review also discusses how to calculate vibrational and elastic properties. Finally, we present a perspective on future uses of first-principles calculations for modeling molecular crystals and summarize the many remaining challenges in this field. [less ▲] Detailed reference viewed: 135 (8 UL)"... weil die meisten Comics einfach zu schwer sind!" - Zur Kategorie der Einfachheit beim Einsatz von Bandes dessinées im Fremdsprachenunterricht Französisch Morys, Nancy in Burwitz-Melzer, Eva; O´Sullivan, Emer (Eds.) Einfachheit in der Kinder- und Jugendliteratur - Ein Gewinn für den Fremdsprachenunterricht (2016, December 18) Detailed reference viewed: 66 (2 UL)Sproochepolitik: Et gëtt keng einfach Léisungen Ugen, Sonja Speeches/Talks (2016) Detailed reference viewed: 22 (3 UL)Single station Monitoring of Volcanoes Using Seismic ambient noise De Plaen, Raphaël ; ; et al Poster (2016, December 16) Detailed reference viewed: 91 (10 UL)Images of Galois representations and p-adic models of Shimura curves Amoros Carafi, Laia Doctoral thesis (2016) The thesis treats two questions situated in the Langlands program, which is one of the most active and important areas in current number theory and arithmetic geometry. The first question concerns the ... [more ▼] The thesis treats two questions situated in the Langlands program, which is one of the most active and important areas in current number theory and arithmetic geometry. The first question concerns the study of images of Galois representations into Hecke algebras coming from modular forms over finite fields, and the second one deals with p-adic models of Shimura curves and its bad reduction. Consequently, the thesis is divided in two parts. The first part is concerned with the study of images of Galois representations that take values in Hecke algebras of modular forms over finite fields. The main result of this part is a complete classification of the possible images of 2-dimensional Galois representations with coefficients in local algebras over finite fields under the hypotheses that: (i) the square of the maximal ideal is zero, (ii) that the residual image is big (in a precise sense), and (iii) that the coefficient ring is generated by the traces. In odd characteristic, the image is completely determined by these conditions; in even characteristic the classification is much richer. In this case, the image is uniquely determined by the number of different traces of the representation, a number which is given by an easy formula. As an application of these results, the existence of certain p-elementary abelian extensions of big non-solvable number fields can be deduced. Whereas some aspects of class field theory are accessible through this approach, it can be applied to huge fields for which standard techniques totally fail. The second part of the thesis consists of an approach to p-adic uniformisations of Shimura curves X(Dp,N) through a combination of different techniques concerning rigid analytic geometry and arithmetic of quaternion orders. The results in this direction lean on two methods: one is based on the information provided by certain Mumford curves covering Shimura curves and the second one on the study of Eichler orders of level N in the definite quaternion algebra of discriminant D. Combining these methods, an explicit description of fundamental domains associated to p-adic uniformisation of families of Shimura curves of discriminant Dp and level N ≥ 1, for which the one-sided ideal class number h(D,N) is 1, is given. The method presented in this thesis enables one to find Mumford curves covering Shimura curves, together with a free system of generators for the associated Schottky groups, p-adic good fundamental domains and their stable reduction-graphs. As an application, general formulas for the reduction-graphs with lengths at p of the considered families of Shimura curves can be computed. [less ▲] Detailed reference viewed: 90 (18 UL)On horizontal and vertical categorifications of Leibniz algebras Poncin, Norbert Presentation (2016, December 16) Detailed reference viewed: 41 (3 UL)Household Nonemployment, Social Risks and Inequality in Europe Hubl, Vanessa Julia Doctoral thesis (2016) The dissertation explores interactions between households, states and markets and their relation to socio-economic inequalities among working-age households. The focus lies on three aspects: the ... [more ▼] The dissertation explores interactions between households, states and markets and their relation to socio-economic inequalities among working-age households. The focus lies on three aspects: the importance of the welfare state, economic risks and opportunities within households, and the link between these two aspects and broader patterns of inequality at the societal level. These are analysed in three empirical studies, using a range of statistical methods (multilevel analysis, event history models and counterfactual analyses of income distributions). In addition, an extensive framework paper provides a background to the analyses, clarifies their relation in theoretical terms, and discusses the results. The first empirical study explores the relation between the regulation of social benefits, social risks, and household nonemployment in 20 European countries using internationally comparative institutional and survey data. The study reveals that eligibility conditions and activation policy vary systematically with the effect of social risks on the probability of household nonemployment. The strength and direction of influence depends on the specific policy area and risk factor. The second study analyses the duration of household nonemployment for British and German couples from the early 1990s to the mid-2000s. Dual joblessness has become longer over time, which is related to changes in the household composition of nonemployed couples. The third analysis evaluates the consequences of welfare shifts between households on changing patterns of inequality between 2005 and 2010. Changes in the distribution of household employment, benefit transfers, and family types in Germany, the United Kingdom, Poland, and Spain are analysed in terms of their contribution to developments in income inequality between households. The analysis of income distributions suggests that changes in socio-demographic and economic household characteristics in a population can have a substantial impact on different income groups. The overarching conclusion of the dissertation is that certain aspects of household composition enhance the risk of lower economic activity and welfare but that the impact of these factors varies strongly according to the broader context the households are situated in. Social policies that have the potential to reduce inequalities between households need to consider possible adverse effects on economic risk structures and spill-over effects to other areas of social protection. Future research should continue studying the household’s role in relation to the market, the state, and individual needs and resources; incorporate additional economic and welfare regime aspects into the analyses; and explore further statistical tools to do so. [less ▲] Detailed reference viewed: 56 (14 UL)De la crise de solidarité au socle européen des droits sociaux: vers une Union économique, monétaire et sociale? Muñoz, Susana Scientific Conference (2016, December 16) This paper examines the "crisis of solidarity" as a consequence of the multidimensional crisis that has struck the world since 2007, and the integrative role of social rights in the European economic ... [more ▼] This paper examines the "crisis of solidarity" as a consequence of the multidimensional crisis that has struck the world since 2007, and the integrative role of social rights in the European economic integration. [less ▲] Detailed reference viewed: 17 (0 UL)A Model-Based Development Environment for Rapid-Prototyping of Latency-Sensitive Automotive Control Software Sundharam, Sakthivel Manikandan ; ; et al in Proceedings of 6th Intentional Symposium on Embedded computing & system Design (ISED 2016) (2016, December 15) The innovation in the field of automotive embedded systems has been increasingly relying on software-implemented functions. The control laws of these functions typically assume deterministic sampling ... [more ▼] The innovation in the field of automotive embedded systems has been increasingly relying on software-implemented functions. The control laws of these functions typically assume deterministic sampling rates and constant delays from input to output. However, on the target processors, the execution times of the software will depend on many factors such as the amount of interferences from other tasks, resulting in varying delays from sensing to actuating. Three approaches supported by tools, namely TrueTime, T-Res, and SimEvents, have been developed to facilitate the evaluation of how timing latencies affect control performance. However, these approaches support the simulation of control algorithms, but not their actual implementation. In this paper, we present a model interpretation engine running in a co-simulation environment to study control performances while considering the run-time delays in to account. Introspection features natively available facilitate the implementation of self-adaptive and fault-tolerance strategies to mitigate and compensate the run-time latencies. A DC servo controller is used as a supporting example to illustrate our approach. Experiments on controller tasks with injected delays show that our approach is on par with the existing techniques with respect to simulation. We then discuss the main benefits of our development approach that are the support for rapid-prototyping and the re-use of the simulation model at run-time, resulting in productivity and quality gains. [less ▲] Detailed reference viewed: 166 (41 UL)Herrschaft in wessen Interesse? Herzöge, Pfandherren und lokale Eliten im Streit um das Herzogtum Luxemburg Dönges, Christa Annette Scientific Conference (2016, December 15) Detailed reference viewed: 13 (0 UL)A performance evaluation of weight-constrained conditioned portfolio optimization Schiltz, Jang ; Scientific Conference (2016, December 15) Detailed reference viewed: 26 (0 UL)A variational formulation of dissipative quasicontinuum methods ; Beex, Lars ; et al in International Journal of Solids and Structures (2016), 102-103 Lattice systems and discrete networks with dissipative interactions are successfully employed as meso-scale models of heterogeneous solids. As the application scale generally is much larger than that of ... [more ▼] Lattice systems and discrete networks with dissipative interactions are successfully employed as meso-scale models of heterogeneous solids. As the application scale generally is much larger than that of the discrete links, physically relevant simulations are computationally expensive. The QuasiContinuum (QC) method is a multiscale approach that reduces the computational cost of direct numerical simulations by fully resolving complex phenomena only in regions of interest while coarsening elsewhere. In previous work (Beex et al., J. Mech. Phys. Solids 64, 154-169, 2014), the originally conservative QC methodology was generalized to a virtual-power-based QC approach that includes local dissipative mechanisms. In this contribution, the virtual-power-based QC method is reformulated from a variational point of view, by employing the energy-based variational framework for rate-independent processes (Mielke and Roub cek, Rate-Independent Systems: Theory and Application, Springer-Verlag, 2015). By construction it is shown that the QC method with dissipative interactions can be expressed as a minimization problem of a properly built energy potential, providing solutions equivalent to those of the virtual-power-based QC formulation. The theoretical considerations are demonstrated on three simple examples. For them we verify energy consistency, quantify relative errors in energies, and discuss errors in internal variables obtained for different meshes and two summation rules. [less ▲] Detailed reference viewed: 74 (8 UL) |
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