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Typical response of quantum pure states Fresch, Barbara ; in European Physical Journal B -- Condensed Matter (2013), 86 Detailed reference viewed: 20 (2 ULg)A wavelet-based mode decomposition Nicolay, Samuel in European Physical Journal B -- Condensed Matter (2011), 80 We propose a wavelet-based method for analyzing non-stationary data. The idea, inspired by the empirical mode decomposition, is to decompose a data set into a ﬁnite number of components, well separated in ... [more ▼] We propose a wavelet-based method for analyzing non-stationary data. The idea, inspired by the empirical mode decomposition, is to decompose a data set into a ﬁnite number of components, well separated in the time-frequency plane, plus a residue, such that each component has a zero mean and is associated to one frequency only. When applied to climatic data, this method gives interesting results. [less ▲] Detailed reference viewed: 64 (23 ULg)Electronic properties and quantum transport in Graphene-based nanostructures ; Zanolli, Zeila ; et al in European Physical Journal B -- Condensed Matter (2009), 72(1), 1-24 Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent a novel class of low-dimensional materials. All these graphene-based nanostructures are expected to display the extraordinary electronic ... [more ▼] Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent a novel class of low-dimensional materials. All these graphene-based nanostructures are expected to display the extraordinary electronic, thermal and mechanical properties of graphene and are thus promising candidates for a wide range of nanoscience and nanotechnology applications. In this paper, the electronic and quantum transport properties of these carbon nanomaterials are reviewed. Although these systems share the similar graphene electronic structure, confinement effects are playing a crucial role. Indeed, the lateral confinement of charge carriers could create an energy gap near the charge neutrality point, depending on the width of the ribbon, the nanotube diameter, the stacking of the carbon layers regarding the different crystallographic orientations involved. After reviewing the transport properties of defect-free systems, doping and topological defects (including edge disorder) are also proposed as tools to taylor the quantum conductance in these materials. Their unusual electronic and transport properties promote these carbon nanomaterials as promising candidates for new building blocks in a future carbon-based nanoelectronics, thus opening alternatives to present silicon-based electronics devices. [less ▲] Detailed reference viewed: 48 (3 ULg)Clusters in weighted macroeconomic networks: the EU case. Introducing the overlapping index of GDP/capita fluctuation correlations ; Ausloos, Marcel in European Physical Journal B -- Condensed Matter (2008), 63(4), 533-539 GDP/capita correlations are investigated in various time windows (TW), for the time interval 1990-2005. The target group of countries is the set of 25 EU members, 15 till 2004 plus the 10 countries which ... [more ▼] GDP/capita correlations are investigated in various time windows (TW), for the time interval 1990-2005. The target group of countries is the set of 25 EU members, 15 till 2004 plus the 10 countries which joined EU later on. The TW-means of the statistical correlation coefficients are taken as the weights (links) of a fully connected network having the countries as nodes. Thereafter we de. ne and introduce the overlapping index of weighted network nodes. A cluster structure of EU countries is derived from the statistically relevant eigenvalues and eigenvectors of the adjacency matrix. This may be considered to yield some information about the structure, stability and evolution of the EU country clusters in a macroeconomic sense. [less ▲] Detailed reference viewed: 15 (1 ULg)Effects of agents' mobility on opinion spreading in Sznajd model ; ; Ausloos, Marcel in European Physical Journal B -- Condensed Matter (2008), 66(1), 115-124 Under synchronous updating and allowing the agents to move in the lattice or underlying network, we find that the Sznajd model always reaches a consensus as a steady state, - because agent frustrations ... [more ▼] Under synchronous updating and allowing the agents to move in the lattice or underlying network, we find that the Sznajd model always reaches a consensus as a steady state, - because agent frustrations are removed due to their diffusion. Moreover, we succeed in obtaining the well-known phase transition of the traditional Sznajd model, which depends on the initial concentration of individuals following an opinion. How the time for reaching consensus depends on the system size, and on the topology have been exhaustively investigated. The analyzed topologies were: annealed and quenched dilution on a square lattice, as well as on a variant of the well-known Barabasi-Albert model, called triad network. [less ▲] Detailed reference viewed: 10 (0 ULg)On the use of Galerkin-Eckhaus method to study the nonlinear regime of Marangoni-Benard instabilities in an evaporating liquid layer ; ; Dauby, Pierre in European Physical Journal B -- Condensed Matter (2006), 54(4), 485-492 Detailed reference viewed: 7 (0 ULg)Networks of equities in financial markets ; ; et al in European Physical Journal B -- Condensed Matter (2004), 38(2), 363-371 We review the recent approach of correlation based networks of financial equities. We investigate portfolio of stocks at different time horizons, financial indices and volatility time series and we show ... [more ▼] We review the recent approach of correlation based networks of financial equities. We investigate portfolio of stocks at different time horizons, financial indices and volatility time series and we show that meaningful economic information can be extracted from noise dressed correlation matrices. We show that the method can be used to falsify widespread market models by directly comparing the topological properties of networks of real and artificial markets. [less ▲] Detailed reference viewed: 16 (0 ULg)Dynamic regimes in films with a periodic array of antidots Silhanek, Alejandro ; ; et al in European Physical Journal B -- Condensed Matter (2004), 37(1), 19-24 We have studied the dynamic response of Pb thin films with a square array of antidots by means of ac susceptibility chi(T,H) measurements. At low enough ac drive amplitudes h, vortices moving inside the ... [more ▼] We have studied the dynamic response of Pb thin films with a square array of antidots by means of ac susceptibility chi(T,H) measurements. At low enough ac drive amplitudes h, vortices moving inside the pinning potential give rise to a frequency- and h-independent response together with a scarce dissipation. For higher amplitudes, the average distance travelled by vortices surpasses the pinning range and a critical state develops. We found that the boundary h*(H,T) between these regimes smoothly decreases as T increases whereas a step-like behavior is observed as a function of field. We demonstrate that these steps in h*(H) arise from sharp changes in the pinning strength corresponding to different vortex configurations. For a wide set of data at several fields and temperatures in the critical state regime, we show that the scaling laws based on the simple Bean model are satisfied. [less ▲] Detailed reference viewed: 16 (2 ULg)Limit current density in 2D metallic granular packings Dorbolo, Stéphane ; Ausloos, Marcel ; Vandewalle, Nicolas in European Physical Journal B -- Condensed Matter (2003), 34(2), 201-204 The electrical properties of a 2D packed metallic pentagons have been studied. The electrical characterization of such metallic pentagon heaps, like i - V measurements, has been achieved. Two distinct ... [more ▼] The electrical properties of a 2D packed metallic pentagons have been studied. The electrical characterization of such metallic pentagon heaps, like i - V measurements, has been achieved. Two distinct regimes have been shown. They are separated by a transition line along which the system exhibits a memory effect behavior due to the irreversible improvement of electrical contacts between pentagons (hot spots). A limit current density has been found. [less ▲] Detailed reference viewed: 42 (7 ULg)Foam imbibition in microgravity - An experimental study Caps, Hervé ; ; et al in European Physical Journal B -- Condensed Matter (2003), 33(1), 115-119 We report an experimental study of aqueous foam imbibition in microgravity with strict mass conservation. The foam is in a Hele-Shaw cell. The bubble edge width l is measured by image analysis. The ... [more ▼] We report an experimental study of aqueous foam imbibition in microgravity with strict mass conservation. The foam is in a Hele-Shaw cell. The bubble edge width l is measured by image analysis. The penetration of the liquid in the foam, the foam imbibition, the foam inflation, and the rigidity loss are shown all to obey strict diffusion processes. The motion of bubbles needed for the foam inflation is a slow two-dimensional process with respect to the one-dimensional capillary rise of liquid. The foam is found to imbibes faster than it inflates. [less ▲] Detailed reference viewed: 19 (3 ULg)Thermal instability of a rotating saturated porous medium heated from below and submitted to rotation Desaive, Thomas ; ; Lebon, Georgy in European Physical Journal B -- Condensed Matter (2002), 29(4), 641-647 In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below. The effect of rotation is restricted to the Coriolis force, neglecting thus the ... [more ▼] In this work, we study the problem of onset of thermal convection in a rotating saturated porous medium heated from below. The effect of rotation is restricted to the Coriolis force, neglecting thus the centrifugal effects, the porous medium is described by Brinkman's model. The linear eigenvalue problem is solved by means of a modified Galerkin method. The behavior of the critical temperature gradient is discussed in terms of various parameters of the system for both stationary and overstable convections. Finally a weakly nonlinear analysis is provided to derive amplitude equations and to study the onset of Kuppers-Lortz instability. [less ▲] Detailed reference viewed: 28 (1 ULg)Domino effect for world market fluctuations Vandewalle, Nicolas ; ; in European Physical Journal B -- Condensed Matter (2000), 15(3), 547-549 In order to emphasize cross-correlations for fluctuations in major market places, series of up and down spins are built from financial data. Patterns frequencies are measured, and statistical tests ... [more ▼] In order to emphasize cross-correlations for fluctuations in major market places, series of up and down spins are built from financial data. Patterns frequencies are measured, and statistical tests performed. Strong cross-correlations are emhasized, proving that market moves are collective behaviors. [less ▲] Detailed reference viewed: 18 (2 ULg)A new universality for random sequential deposition of needles Vandewalle, Nicolas ; ; in European Physical Journal B -- Condensed Matter (2000), 14(3), 407-410 Percolation and jamming phenomena are investigated for random sequential deposition of rectangular needles on d = 2 square lattices. Associated thresholds p(c)(perc) and p(c)(jam) are determined for ... [more ▼] Percolation and jamming phenomena are investigated for random sequential deposition of rectangular needles on d = 2 square lattices. Associated thresholds p(c)(perc) and p(c)(jam) are determined for Various needle sizes. Their ratios p(c)(perc)/p(c)(jam) are found to be a constant 0.62 +/- 0.01 for all sizes. In addition the ratio of jamming thresholds for respectively square blocks and needles is also found to be a constant 0.79 +/- 0.01. These constants exhibit some universal connexion in the geometry of jamming and percolation for both anisotropic shapes (needles versus square lattices) and isotropic shapes (square blocks on square lattices). A universal empirical law is proposed for all three thresholds as a function of alpha. [less ▲] Detailed reference viewed: 16 (2 ULg)Simultaneous measurements of thermal diffusivity, thermal conductivity and thermopower with application to copper and ceramic superconductors Bougrine, Hassan ; ; Dorbolo, Stéphane et al in European Physical Journal B -- Condensed Matter (2000), 13(3), 437-443 A home made experimental set-up allows us to measure the thermal conductivity, the thermopower and the thermal diffusivity simultaneously in the temperature range (20-300 K). Therefore the specific heat ... [more ▼] A home made experimental set-up allows us to measure the thermal conductivity, the thermopower and the thermal diffusivity simultaneously in the temperature range (20-300 K). Therefore the specific heat can be deduced. The role of a radiation shield is shown to be relevant. Tests of the system are made on a 99.9% pure Cu sample and two polycrystalline cuprate ceramics for illustration. Without any complicated optimisation, the technique indicates much promise already due to its efficiency and rapidity. [less ▲] Detailed reference viewed: 73 (13 ULg)Visualizing the log-periodic pattern before crashes Vandewalle, Nicolas ; Ausloos, Marcel ; et al in European Physical Journal B -- Condensed Matter (1999), 9(2), 355-359 We present a method for visualizing the pattern which we believe to be a precursor signature of financial crashes (or ruptures). The log-periodicity of the pattern is investigated through the envelope ... [more ▼] We present a method for visualizing the pattern which we believe to be a precursor signature of financial crashes (or ruptures). The log-periodicity of the pattern is investigated through the envelope function technique. Three periods of the Down Jones Industrial Average (DJIA) are investigated: 1982-1987, 1992-1997 and 1993-1998. The presence of a rupture in the end of 1998 is outlined from data taken before the end of August 1998. [less ▲] Detailed reference viewed: 39 (2 ULg)Multi-affine analysis of typical currency exchange rates Vandewalle, Nicolas ; Ausloos, Marcel in European Physical Journal B -- Condensed Matter (1998), 4(2), 257-261 For foreign currency exchange rates; multi-affine analysis can put quantitatively into evidence the differences between correlated (daily closing market) values and random walks in time dependent data ... [more ▼] For foreign currency exchange rates; multi-affine analysis can put quantitatively into evidence the differences between correlated (daily closing market) values and random walks in time dependent data. The H(q) spectrum is presented and discussed here for the USD/DEM and JPY/USD exchange rates. The time-evolution of these ratios is found to be multi-affine. The h(gamma)-curve describing the hierarchy of exponents is numerically obtained. Our findings suggest that the modelling of exchange rate time-evolution from day to day is possible within the framework of modern statistical physics and related to models of turbulence in the physics of fluids. Finally, we argue that there is a multiplicity of information levels in the foreign exchange market such that the "efficient market theory" is a crude oversimplification indeed. [less ▲] Detailed reference viewed: 32 (1 ULg)How the financial crash of October 1997 could have been predicted Vandewalle, Nicolas ; Ausloos, Marcel ; et al in European Physical Journal B -- Condensed Matter (1998), 4(2), 139-141 From the analysis of (closing value) stock market index like the Dow Jones Industrial average and the S&P500 it is possible to observe the precursor of a so-called crash. This is shown on the Oct. 1987 ... [more ▼] From the analysis of (closing value) stock market index like the Dow Jones Industrial average and the S&P500 it is possible to observe the precursor of a so-called crash. This is shown on the Oct. 1987 and Oct. 1997 cases. The data analysis indicates that the index divergence has followed twice a "universal"; behavior, i.e. a logarithmic dependence, superposed on a well defined oscillation pattern. The prediction of the crash date is remarkable and can be done two months in advance. In the spirit of phase transition phenomena, the economic index is said to be analogous to a signal signature found in a two dimensional fluid of vortices. [less ▲] Detailed reference viewed: 44 (2 ULg) |
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