References of "Dorbolo, Stéphane"
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See detailRolling and slipping motion of Euler's disk
Caps, Hervé ULg; Dorbolo, Stéphane ULg; Ponte, S. et al

in Physical Review E (2004), 69(5, Pt 2), 56610

We present an experimental study of the motion of a circular disk spun onto a table. With the help of a high speed video system, the temporal evolution of (i) the inclination angle alpha, (ii) the angular ... [more ▼]

We present an experimental study of the motion of a circular disk spun onto a table. With the help of a high speed video system, the temporal evolution of (i) the inclination angle alpha, (ii) the angular velocity omega, and (iii) the precession rate Omega are studied. The influence of the mass of the disk as well as the friction between the disk and the supporting surface are considered. Both inclination angle and angular velocity are observed to decrease according to a power law. We also show that the precession rate diverges as the motion stops. Measurements are performed very near the collapse as well as on long range times. Times to collapse have been also measured. Results are compared with previous theoretical and experimental works. The major source of energy dissipation is found to be the slipping of the disk on the plane. [less ▲]

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See detailEffects of silicon addition on the electrical and magnetic properties of copper-doped (La,Ca)MnO3 compounds
Vertruyen, Bénédicte ULg; Rulmont, André ULg; Cloots, Rudi ULg et al

in Journal of Magnetism and Magnetic Materials (2004), 268(3), 364-373

In this paper we report about the electrical properties of La0.7Ca0.3MnO3 compounds substituted by copper on the manganese site and/or deliberately contaminated by SiO2 in the reactant mixture. Several ... [more ▼]

In this paper we report about the electrical properties of La0.7Ca0.3MnO3 compounds substituted by copper on the manganese site and/or deliberately contaminated by SiO2 in the reactant mixture. Several phenomena have been observed and discussed. SiO2 addition leads to the formation of an apatite-like secondary phase that affects the electrical conduction through the percolation of the charge carriers. On the other hand, depending on the relative amounts of copper and silicon, the temperature dependence of the electrical resistivity can be noticeably modified: our results enable us to compare the effects of crystallographic vacancies on the A and B sites of the perovskite with the influence of the copper ions substituted on the manganese site. The most original result occurs for the compounds with a small ratio Si/Cu, which display double-peaked resistivity vs. temperature curves. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailAnalysis of experimental conditions for simultaneous measurements of transport and magnetotransport coefficients of high temperature superconductors
Mucha, J.; Dorbolo, Stéphane ULg; Bougrine, Hassan ULg et al

in Cryogenics (2004), 44(3), 145-149

Experimental conditions for simultaneous measurements of transport coefficients of high temperature superconductors in zero and non-zero magnetic fields are analysed. Test measurements of the thermal ... [more ▼]

Experimental conditions for simultaneous measurements of transport coefficients of high temperature superconductors in zero and non-zero magnetic fields are analysed. Test measurements of the thermal conductivity, the thermoelectric power and the Nernst-Ettingshausen effect of a textured Bi2212 sample are reported in an external magnetic field of 2 T. Errors related to parameters of the thermocouple used and to the spurious heat flows are discussed for a new experimental set-up built based on a closed cycle helium refrigerator. Possible optimising of experimental conditions is suggested. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailFluid instabilities in the birth and death of antibubbles
Dorbolo, Stéphane ULg; Caps, Hervé ULg; Vandewalle, Nicolas ULg

in New Journal of Physics (2003), 5

Antibubbles have been produced and studied with the help of a high-speed camera. An antibubble is defined as a fluid object constituted by a thin air shell surrounding a liquid and surrounded by the same ... [more ▼]

Antibubbles have been produced and studied with the help of a high-speed camera. An antibubble is defined as a fluid object constituted by a thin air shell surrounding a liquid and surrounded by the same liquid. Images reveal some key physical processes and fluid instabilities which take place when an antibubble forms and dies. The collapsing speed of the air film has been measured. Culik's theory does not apply. A new mechanism has been introduced. [less ▲]

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See detailAging process of electrical contacts in granular matter
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg; Vandewalle, Nicolas ULg et al

in Journal of Applied Physics (2003), 94(12), 7835-7838

The electrical resistance decay of a metallic granular packing has been measured as a function of time. This measurement gives information about the size of the conducting cluster formed by the well ... [more ▼]

The electrical resistance decay of a metallic granular packing has been measured as a function of time. This measurement gives information about the size of the conducting cluster formed by the well connected grains. Several regimes have been encountered. Chronologically, the first one concerns the growth of the conducting cluster and is identified to belong to diffusion processes through a stretched exponential behavior. The relaxation time is found to be simply related to the initial injected power. This regime is followed by a reorganization process due to thermal dilatation. For the long-term behavior of the decay, an aging process occurs and enhances the electrical contacts between grains through microsoldering. (C) 2003 American Institute of Physics. [less ▲]

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See detailLimit current density in 2D metallic granular packings
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg; Vandewalle, Nicolas ULg

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 ▲]

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See detailBehavior of bulk melt-textured YBCO single domains subjected to crossed magnetic fields
Vanderbemden, Philippe ULg; Dorbolo, Stéphane ULg; Hari-Babu, N. et al

in IEEE Transactions on Applied Superconductivity (2003), 13(2, Part 3), 3746-3749

We have experimentally investigated the crossed magnetic field effects on bulk melt-processed YBCO single domains. The samples were first permanently magnetized along their c-axis and then subjected to ... [more ▼]

We have experimentally investigated the crossed magnetic field effects on bulk melt-processed YBCO single domains. The samples were first permanently magnetized along their c-axis and then subjected to several cycles of a transverse magnetic field parallel to the ab planes. The magnetic properties along the c and ab directions were simultaneously measured using a couple of orthogonal pick-up coils as well as a Hall probe placed against the sample surface. The effects of both sweep amplitude and polarity were investigated. Field sweeps of alternate polarities are shown to affect the decay of the c-axis magnetization much more strongly than field sweeps of unique polarity do. However, the c-axis magnetization does not show any saturation even after a large number of field sweeps. Next, a micro-Hall probe scanning system was used to measure the distribution of magnetic induction over the top surface of the single domain subjected to the same combination of magnetic fields. The results are shown to be consistent with those determined with the sensing coils and bring out the role played by geometric effects. (C) 2003 IEEE. [less ▲]

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See detailReexamination of the Branly effect
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg; Vandewalle, Nicolas ULg

in Physical Review E (2003), 67(4, Pt 1), 40302

The electrical resistance of a metallic granular packing has been recorded at room temperature. A nearby burster between which sparks are produced, induces a decrease in the resistance of the granular ... [more ▼]

The electrical resistance of a metallic granular packing has been recorded at room temperature. A nearby burster between which sparks are produced, induces a decrease in the resistance of the granular packing as described in the works of Branly. Our measurements emphasize that the decrease is continuous and the resistance variations behave like a stretched exponential law due to the creation of new electrical paths as in nucleation-growth soldering processes. This behavior has been identified to be a diffusionlike process. [less ▲]

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See detailA Modified Tetris Model Including The Effect of Friction
Ludewig, François ULg; Dorbolo, Stéphane ULg; Caps, Hervé ULg et al

in Traffic and Granular Flow'03 (2003)

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See detailSynthesis of CMR manganate compounds: the consequences of the choice of a precursor method
Vertruyen, Bénédicte ULg; Rulmont, André ULg; Cloots, Rudi ULg et al

in Materials Letters (2002), 57(3), 598-603

We have studied the electrical transport properties of manganate samples synthesized by different precursor methods. Differences in the synthesis process of the materials can result in samples with ... [more ▼]

We have studied the electrical transport properties of manganate samples synthesized by different precursor methods. Differences in the synthesis process of the materials can result in samples with similar grain size but very different physical properties, contrary to what happens in samples prepared by the same method. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailCascades of popping bubbles
Vandewalle, Nicolas ULg; Caps, Hervé ULg; Dorbolo, Stéphane ULg

in Physica A: Statistical Mechanics and its Applications (2002), 314(1-4), 320-324

We study the intermittent dynamics of collapsing foams. Avalanches of popping bubbles are observed. Although correlations between successive popping bubbles are emphasized, film raptures at the air/foam ... [more ▼]

We study the intermittent dynamics of collapsing foams. Avalanches of popping bubbles are observed. Although correlations between successive popping bubbles are emphasized, film raptures at the air/foam interface seem to be independent of the bubble size. Possible mechanisms for cascades of bubble pops are proposed and discussed. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailMagnon-polaron and spin-polaron signatures in the specific heat and electrical resistivity of La0.6Y0.1Ca0.3MnO3 in zero magnetic field and the effect of Mn - O - Mn bond environment
Ausloos, Marcel ULg; Hubert, L.; Dorbolo, Stéphane ULg et al

in Physical Review B (2002), 66(17),

La0.6Y0.1Ca0.3MnO3, an ABO(3) perovskite manganite oxide, exhibits a nontrivial behavior in the vicinity of the sharp peak found in the resistivity rho as a function of temperature T in zero magnetic ... [more ▼]

La0.6Y0.1Ca0.3MnO3, an ABO(3) perovskite manganite oxide, exhibits a nontrivial behavior in the vicinity of the sharp peak found in the resistivity rho as a function of temperature T in zero magnetic field. The various features seen on drho/dT are discussed in terms of competing phase transitions. They are related to the Mn-O-Mn bond environment depending on the content of the A crystallographic site. A Ginzburg-Landau type theory is presented for incorporating concurrent phase transitions. The specific heat C of such a compound is also examined from 50 to 200 K. A log-log analysis indicates different regimes. In the low temperature conducting ferromagnetic phase, a collective magnon signature (Csimilar or equal toT(3/2)) is found as for what are called magnon-polaron excitations. A Csimilar or equal toT(2/3) law is found at high temperature and discussed in terms of the fractal dimension of the conducting network of the weakly conducting (so-called insulating) phase and an Orbach estimate of the excitation spectral behaviors. The need of considering both independent spin scattering and collective spin scattering is thus emphasized. The report indicates a remarkable agreement for the Fisher-Langer formula, i.e., Csimilar todrho/dT at second order phase transitions. Within the Attfield model, we find an inverse square root relationship between the critical temperature(s) and the total local Mn-O-Mn strain. [less ▲]

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See detailElectrical investigations of granular arches
Dorbolo, Stéphane ULg; Vandewalle, Nicolas ULg

in Physica A: Statistical Mechanics and its Applications (2002), 311(3-4), 307-312

Compaction dynamics and granular arches have been studied using the electrical resistance of a packing. An exponential decay of the resistance is found whatever the electrical current is. A fluctuation ... [more ▼]

Compaction dynamics and granular arches have been studied using the electrical resistance of a packing. An exponential decay of the resistance is found whatever the electrical current is. A fluctuation regime is then encountered. A characteristic relaxation time has been pointed out and is linked to the arch formation in the system. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailHysteretic behavior in metallic granular matter
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg; Vandewalle, Nicolas ULg

in Applied Physics Letters (2002), 81(5), 936-938

Various packings made of metallic grains have been electrically characterized. Electrical breakdown is observed in I-V curves. A well defined critical point separates the insulating and the conducting ... [more ▼]

Various packings made of metallic grains have been electrically characterized. Electrical breakdown is observed in I-V curves. A well defined critical point separates the insulating and the conducting regime of the packing. The breakdown is reversible by submitting the packing to a small tap. This unusual property leads to hysteretic loops in I-V diagrams. The study of the behavior of I-V curves allows us to describe the system as a network of weak lossy contacts. The key parameter is the inner electrical field controlling the diode-like or diffusion-like state of the packing. (C) 2002 American Institute of Physics. [less ▲]

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See detailInfluence of a low magnetic field on the thermal diffusivity of Bi2Sr2CaCu2O8
Dorbolo, Stéphane ULg; Ausloos, Marcel ULg

in Physical Review B (2002), 65(21),

The thermal diffusivity of a Bi-2212 polycrystalline sample has been measured under a 1 T magnetic field applied perpendicularly to the heat flux. The magnetic contribution to the heat carrier mean free ... [more ▼]

The thermal diffusivity of a Bi-2212 polycrystalline sample has been measured under a 1 T magnetic field applied perpendicularly to the heat flux. The magnetic contribution to the heat carrier mean free path has been extracted and is found to behave as a simple power law. This behavior can be attributed to a percolation process of electrons in the vortex lattice created by the magnetic field. [less ▲]

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See detailCu doping as a tool for understanding CMR
Vertruyen, Bénédicte ULg; Cloots, Rudi ULg; Rulmont, André ULg et al

in Key Engineering Materials [=KEM] (2002), 206-2

Doping at the Mn-site in CMR manganate-based perovskites has been shown to affect strongly the physical properties of those compounds. We study here the effect of copper substitution in the low doping ... [more ▼]

Doping at the Mn-site in CMR manganate-based perovskites has been shown to affect strongly the physical properties of those compounds. We study here the effect of copper substitution in the low doping range on the electrical transport properties of La0.7Ca0.3MnO3. It turns out that the transition temperature decrease observed in doped samples can be drastically reduced by addition of silicon dioxide SiO2. It is shown that copper is trapped in a secondary phase composed of La,Ca,Si,Cu and O. The resultant Mn-site vacancies appear to be less detrimental to the electronic conduction than the likely antiferromagnetic clusters induced by the copper ions in the Mn-O network. [less ▲]

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See detailGiant electrical fluctuations in metallic disordered packings
Vandewalle, Nicolas ULg; Dorbolo, Stéphane ULg

in European Physical Journal E -- Soft Matter (2001), 5(2), 129-131

We have experimentally studied granular arches through electrical measurements. The packing is composed of 2d metallic pentagons and is submitted to small taps. Large electrical fluctuations are observed ... [more ▼]

We have experimentally studied granular arches through electrical measurements. The packing is composed of 2d metallic pentagons and is submitted to small taps. Large electrical fluctuations are observed and they are distributed along power laws. The indicates the presence of long-time memory effects event the packing density remains constant around a value rho = 0.72 +/- 0.02. Large electrical fluctuations should be associated with the breaking/creation of granular arches. [less ▲]

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See detailAvalanches of Popping Bubbles in Collapsing Foams
Vandewalle, Nicolas ULg; Lentz, J. F.; Dorbolo, Stéphane ULg et al

in Physical Review Letters (2001), 86(1), 179-82

We report acoustic measurements of popping bubbles during the collapsing of aqueous foams. The sound pattern is analyzed using classical methods of statistical physics. It is found that membrane rupture ... [more ▼]

We report acoustic measurements of popping bubbles during the collapsing of aqueous foams. The sound pattern is analyzed using classical methods of statistical physics. It is found that membrane rupture concerns a wide variety of situations: small and large membranes at the air/foam interface. Avalanches of popping bubbles are put into evidence. Time durations in between successive pops seem to be distributed on a universal power law. [less ▲]

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See detailNon-Gaussian electrical fluctuations in a quasi-2d packing of metallic beads
Vandewalle, Nicolas ULg; Lenaerts, Cedric ULg; Dorbolo, Stéphane ULg

in Europhysics Letters [=EPL] (2001), 53(2), 197-201

The electrical properties of a two-dimensional packing of metallic beads are studied. Small mechanical perturbations of the packing lead to giant voltage fluctuations. Fluctuations are found to be non ... [more ▼]

The electrical properties of a two-dimensional packing of metallic beads are studied. Small mechanical perturbations of the packing lead to giant voltage fluctuations. Fluctuations are found to be non-Gaussian and seem to belong to Levy stable distributions. Anticorrelations have been also found for the sign of these fluctuations. [less ▲]

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