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Multifonctionnalité en agriculture, attentes et besoins du monde rural : regards croisés Dogot, Thomas Conference (2007) Detailed reference viewed: 12 (4 ULg)A multifractal analysis of air temperature signals based on the wavelet leaders method Deliège, Adrien ; Nicolay, Samuel Conference (2014, August 20) We present the wavelet leaders method (introduced by S. Jaffard) as a tool to study the Hölder regularity of signals, which is closely related to some functional spaces. We use the associated multifractal ... [more ▼] We present the wavelet leaders method (introduced by S. Jaffard) as a tool to study the Hölder regularity of signals, which is closely related to some functional spaces. We use the associated multifractal formalism to show that surface air temperature signals are monofractal, i.e. these are regularly irregular. Then we use this result to establish a climate classification of weather stations in Europe which matches the Köppen-Geiger climate classification. This result could give rise to new criteria to determine the effectiveness of current climatic models. [less ▲] Detailed reference viewed: 31 (8 ULg)Multifractal analysis of air temperature signals using the wavelet leaders method Deliège, Adrien ; Nicolay, Samuel Conference (2014, May 22) We use the discrete "wavelet transform microscope" to show that the surface air temperature signals of weather stations selected in Europe are monofractal. This study reveals that the information obtained ... [more ▼] We use the discrete "wavelet transform microscope" to show that the surface air temperature signals of weather stations selected in Europe are monofractal. This study reveals that the information obtained in this way are richer than previous works studying long range correlations in meteorological stations. The approach presented here allows to bind the Hölder exponents with the climate variability. We also establish that such a link does not exist with methods previously carried out, such as the detrended fluctuation analysis. [less ▲] Detailed reference viewed: 47 (4 ULg)A multifractal formalism based on the Sν spaces: From theory to practice Esser, Céline ; Kleyntssens, Thomas ; Nicolay, Samuel E-print/Working paper (2014) We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non ... [more ▼] We present an implementation of a multifractal formalism based on the Sν spaces and show that it effectively gives the right Hölder spectrum in numerous cases. In particular, it allows to recover non-concave spectra, where other multifractal formalisms only lead to the concave hull of the spectra. [less ▲] Detailed reference viewed: 5 (0 ULg)A multifractal formalism for non-concave and non-increasing spectra: the leaders profile method Esser, Céline ; Kleyntssens, Thomas ; Nicolay, Samuel in Applied & Computational Harmonic Analysis (in press) We present an implementation of a multifractal formalism based on the types of histogram of wavelet leaders. This method yields non-concave spectra and is not limited to their increasing part. We show ... [more ▼] We present an implementation of a multifractal formalism based on the types of histogram of wavelet leaders. This method yields non-concave spectra and is not limited to their increasing part. We show both from the theoretical and from the applied points of view that this approach is more e cient than the wavelet-based multifractal formalisms previously introduced. [less ▲] Detailed reference viewed: 25 (10 ULg)Multifractal properties of pore-size distribution in apple tissue using X-ray imaging ; ; et al in JOURNAL OF FOOD ENGINEERING (2010), 99(2), 206-215 The pore-size distribution (PSD) has an important influence on the complex gas transport phenomena (02 and CO(2)) that occur in apple tissue during storage under controlled atmosphere conditions. It ... [more ▼] The pore-size distribution (PSD) has an important influence on the complex gas transport phenomena (02 and CO(2)) that occur in apple tissue during storage under controlled atmosphere conditions. It defines the apple tissue microstructure that is correlated to many other apple properties. In this article multifractal analysis (MFA) has been used to study the multiscale structure of the PSD using generalized dimensions in three varieties of apples (Jonagold, Greenstar, and Kanzi) based on X-ray imaging technology (8.5 mu m resolution). Tomographic images of apple samples were taken at two positions within the parenchyma tissue: close to the peel and near to the core. The images showed suitable scaling properties. The generalized dimensions were determined with an R(2) greater than 0.98 in the range of moment orders between -1 and +10. The variation of D(q) with respect to q and the shape of the multifractal generalized spectrum revealed that the PSD structure of apple tissue has properties close to multifractal self-similarity measures. Comparisons among cultivars showed that, in spite of the complexity and variability of the pore space of these apple samples, the extracted generalized dimensions from PSD were significantly different (p < 0.05). The generalized dimensions D(0), D(1), D(2), and the quantity D(0)-D(2) could be used to discriminate tissue samples from different positions or cultivars. Also, high correlations were found between these parameters and the porosity (R(2) >= 0.935). These results demonstrate that MFA is an appropriate tool for characterizing the internal pore-size distribution of apple tissue and thus may be used as a quantitative measure to understand how tissue microstructure affects important physical properties of apple. (C) 2010 Elsevier Ltd. All rights reserved. [less ▲] Detailed reference viewed: 37 (0 ULg)Multifractal properties of Pyrex and silicon surfaces blasted with sharp particles ; Kraft, Michaël ; in Physica A: Statistical Mechanics and its Applications (2008), 387(8-9), 2083--2090 The blasting of brittle materials with sharp particles is an important fabrication technology in many industrial processes. In particular, for microsystems, it allows the production of devices with ... [more ▼] The blasting of brittle materials with sharp particles is an important fabrication technology in many industrial processes. In particular, for microsystems, it allows the production of devices with feature sizes down to few tens of microns. An important parameter of this process is the surface roughness of post-blasted surfaces. In this work the scaling properties of Pyrex glass and silicon surfaces after bombardment with alumina particles are investigated. The targets were bombarded at normal incidence using alumina particles with two different average sizes, 29 μm and 9 μm. This investigation indicates that the resulting surfaces are multifractal. Applying multifractal detrended fluctuation analysis (MFDFA) allowed us to determine the singularity spectrum of the surfaces. This spectrum did not depend on the target material or on the size of the particles. Several parameters quantifying relevant quantities were determined. It was found that long range correlations are responsible for the observed multifractal behaviour. [less ▲] Detailed reference viewed: 13 (0 ULg)Multifractal wave functions of simple quantum maps Martin, John ; ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2010), 82 We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like ... [more ▼] We study numerically multifractal properties of two models of one-dimensional quantum maps: a map with pseudointegrable dynamics and intermediate spectral statistics and a map with an Anderson-like transition recently implemented with cold atoms. Using extensive numerical simulations, we compute the multifractal exponents of quantum wave functions and study their properties, with the help of two different numerical methods used for classical multifractal systems (box-counting and wavelet methods). We compare the results of the two methods over a wide range of values. We show that the wave functions of the Anderson map display a multifractal behavior similar to eigenfunctions of the three-dimensional Anderson transition but of a weaker type. Wave functions of the intermediate map share some common properties with eigenfunctions at the Anderson transition (two sets of multifractal exponents, with similar asymptotic behavior), but other properties are markedly different (large linear regime for multifractal exponents even for strong multifractality, different distributions of moments of wave functions, and absence of symmetry of the exponents). Our results thus indicate that the intermediate map presents original properties, different from certain characteristics of the Anderson transition derived from the nonlinear sigma model. We also discuss the importance of finite-size effects. [less ▲] Detailed reference viewed: 26 (8 ULg)A multifractal-based climate analysis Deliège, Adrien ; Nicolay, Samuel Conference (2014, March 25) This work consists of a multifractal analysis of surface air temperature in Western and Eastern Europe. The wavelet leaders method enables us to exhibit the monofractal nature of these signals. Then, we ... [more ▼] This work consists of a multifractal analysis of surface air temperature in Western and Eastern Europe. The wavelet leaders method enables us to exhibit the monofractal nature of these signals. Then, we define a climate classification relying on the Zygmund-Hölder spaces and show that it matches the Köppen classification. By doing so, we evidence the existing relation between the regularity of the temperature data (obtained through functional spaces) and the type of climate. Finally, we give a climatic interpretation of these results. [less ▲] Detailed reference viewed: 56 (24 ULg)Multifractality and intermediate statistics in quantum maps Martin, John ; ; in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2008), 77 We study multifractal properties of wave functions for a one-parameter family of quantum maps displaying the whole range of spectral statistics intermediate between integrable and chaotic statistics. We ... [more ▼] We study multifractal properties of wave functions for a one-parameter family of quantum maps displaying the whole range of spectral statistics intermediate between integrable and chaotic statistics. We perform extensive numerical computations and provide analytical arguments showing that the generalized fractal dimensions are directly related to the parameter of the underlying classical map, and thus to other properties such as spectral statistics. Our results could be relevant for Anderson and quantum Hall transitions, where wave functions also show multifractality. [less ▲] Detailed reference viewed: 20 (5 ULg)Multifractality in quantum maps Martin, John ; ; et al Poster (2010, March) Detailed reference viewed: 11 (4 ULg)Multifractality in the kicked rotator Martin, John ; ; et al Poster (2010, July) Detailed reference viewed: 34 (9 ULg)Multifractality of quantum wave functions Martin, John ; ; et al Poster (2013, March 19) We study the multifractality of individual wave packets in a periodically kicked system through a combination of numerical and analytical works. We consider a version of the mathematical Ruijsenaars ... [more ▼] We study the multifractality of individual wave packets in a periodically kicked system through a combination of numerical and analytical works. We consider a version of the mathematical Ruijsenaars-Schneider model and reinterpreted it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can be tuned by varying a parameter [1]. We compare different methods to measure the multifractality of wave packets and identify the best one. We find the multifractality to decrease with time until it reaches an asymptotic limit, which is different from the multifractality of eigenvectors but related to it, as is the rate of the decrease. Our results could guide the study of experimental situations where multifractality is present in quantum systems. [less ▲] Detailed reference viewed: 29 (7 ULg)Multifractality of quantum wave functions ; ; et al Poster (2013, September) Detailed reference viewed: 27 (3 ULg)Multifractality of quantum wave functions in the presence of perturbations Dubertrand, Rémy ; ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2015), 92 We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a ... [more ▼] We present a comprehensive study of the destruction of quantum multifractality in the presence of perturbations. We study diverse representative models displaying multifractality, including a pseudointegrable system, the Anderson model, and a random matrix model. We apply several types of natural perturbations which can be relevant for experimental implementations. We construct an analytical theory for certain cases and perform extensive large-scale numerical simulations in other cases. The data are analyzed through refined methods including double scaling analysis. Our results confirm the recent conjecture that multifractality breaks down following two scenarios. In the first one, multifractality is preserved unchanged below a certain characteristic length which decreases with perturbation strength. In the second one, multifractality is affected at all scales and disappears uniformly for a strong-enough perturbation. Our refined analysis shows that subtle variants of these scenarios can be present in certain cases. This study could guide experimental implementations in order to observe quantum multifractality in real systems. [less ▲] Detailed reference viewed: 19 (8 ULg)Multifractality of quantum wave packets ; Martin, John ; et al in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 86 We study a version of the mathematical Ruijsenaars-Schneider model and reinterpret it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can ... [more ▼] We study a version of the mathematical Ruijsenaars-Schneider model and reinterpret it physically in order to describe the spreading with time of quantum wave packets in a system where multifractality can be tuned by varying a parameter. We compare different methods to measure the multifractality of wave packets and identify the best one. We find the multifractality to decrease with time until it reaches an asymptotic limit, which is different from the multifractality of eigenvectors but related to it, as is the rate of the decrease. Our results could guide the study of experimental situations where multifractality is present in quantum systems. [less ▲] Detailed reference viewed: 91 (4 ULg)Multifragmentation in reactions of 1-GeV protons with iron nuclei ; ; et al in Journal of Korean Physical Society (2011), 59(2), 943-946 Detailed reference viewed: 8 (0 ULg)Multifunctional architectured materials for electromagnetic absorption ; ; et al in Scripta Materialia (2013), 68(1), 50-54 A sandwich structure involving a honeycomb core filled with a carbon nanotube-reinforced polymer foam and glass fiber-reinforced composite face sheets has been developed in order to combine high ... [more ▼] A sandwich structure involving a honeycomb core filled with a carbon nanotube-reinforced polymer foam and glass fiber-reinforced composite face sheets has been developed in order to combine high electromagnetic absorption and high mechanical performance. The large electromagnetic absorption is attained by simultaneously minimizing the reflection and transmission, which, in terms of effective material properties, requires a low dielectric constant and a conductivity around 1 S m−1. The sandwich offers also high stiffness versus density performance. [less ▲] Detailed reference viewed: 78 (4 ULg)Multifunctional coatings Van de Weerdt, Cécile ; Detrembleur, Christophe ; Jérôme, Robert et al Patent (2009) New polyelectrolyte copolymer, composite material, multilayer film and substrate carrying such polyelectrolyte copolymer, composite and multilayer film wherein the polyelectrolyte copolymer comprises a) a ... [more ▼] New polyelectrolyte copolymer, composite material, multilayer film and substrate carrying such polyelectrolyte copolymer, composite and multilayer film wherein the polyelectrolyte copolymer comprises a) a first type of identical or different units (A) each comprising one or more dihydroxyphenyl groups such that sidechains are present along the backbone of the polyelectrolyte copolymer which contain at least one dihydroxyphenyl group each; and (b1) a second type of identical or different units (B1) each comprising a cationic moiety, or (b2) a second type of identical or different units (B2) each comprising an anionic moiety. [less ▲] Detailed reference viewed: 26 (1 ULg)Multifunctional coatings Van de Weerdt, Cécile ; Detrembleur, Christophe ; et al Patent (2009) Detailed reference viewed: 42 (22 ULg) |
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