Melting of a confined monolayer of magnetized beads

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2013)

Multifractality of quantum wave packets

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 ▲]

How relative humidity affects random packing experiments

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 85

The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has been experimentally investigated. Millimeter-sized glass beads are considered. Compaction ... [more ▼]

The influence of relative humidity (RH) on the extremely slow compaction dynamics of a granular assembly has been experimentally investigated. Millimeter-sized glass beads are considered. Compaction curves are fitted by stretched exponentials with characteristic time τ and exponent δ, which are seen to be deeply affected by the moisture content. A kinetic model, taking into account both triboelectric and capillary effects, is in excellent agreement with our results. It confirms the existence of an optimal condition at a relative humidity ≈45% for minimizing cohesive interactions between glass beads. The exponent δ is seen to depend strongly on the diffusive character of grains and voids inside the packing: diffusion for cohesiveless particles and subdiffusion when cohesion plays a role. As a consequence, the RH represents a relevant parameter that should be reported for every experimental work on a slowly driven dense random packing. [less ▲]

Microstructural degeneracy associated with a two-point correlation function and its information content

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012), 85

A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly differentmicrostructures may have the same correlation function. In an earlier ... [more ▼]

A two-point correlation function provides a crucial yet an incomplete characterization of a microstructure because distinctly differentmicrostructures may have the same correlation function. In an earlier Letter [Gommes, Jiao, and Torquato, Phys. Rev. Lett. 108, 080601 (2012)], we addressed the microstructural degeneracy question: What is the number of microstructures compatible with a specified correlation function? We computed this degeneracy, i.e., configurational entropy, in the framework of reconstruction methods, which enabled us to map the problem to the determination of ground-state degeneracies. Here, we provide a more comprehensive presentation of the methodology and analyses, as well as additional results. Since the configuration space of a reconstruction problem is a hypercube on which a Hamming distance is defined, we can calculate analytically the energy profile of any reconstruction problem, corresponding to the average energy of allmicrostructures at a given Hamming distance from a ground state. The steepness of the energy profile is a measure of the roughness of the energy landscape associated with the reconstruction problem, which can be used as a proxy for the ground-state degeneracy. The relationship between this roughness metric and the ground-state degeneracy is calibrated using a Monte Carlo algorithm for determining the ground-state degeneracy of a variety of microstructures, including realizations of hard disks and Poisson point processes at various densities as well as thosewith known degeneracies (e.g., single disks of various sizes and a particular crystalline microstructure). We show that our results can be expressed in terms of the information content of the two-point correlation functions. From this perspective, the a priori condition for a reconstruction to be accurate is that the information content, expressed in bits, should be comparable to the number of pixels in the unknown microstructure. We provide a formula to calculate the information content of any two-point correlation function, which makes our results broadly applicable to any field in which correlation functions are employed. [less ▲]

How does an ice block assembly melt?

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2012)

Antiphase synchronization of electrically shaken conducting beads

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84

Influence of a reduced gravity on the volume fraction of a monolayer of spherical grains

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84

Single thermal plume in locally heated vertical soap films

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 84

Hysteretic behavior in three-dimensional soap film rearrangements

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2011), 83

Effect of an electric field on an intermittent granular flow

in Physical Review. E : Statistical, Nonlinear, and Soft Matter Physics (2010), 81

Granular gravity driven flows of glass beads have been observed in a silo with a flat bottom. A dc high electric field has been applied perpendicularly to the silo to tune the cohesion. The outlet mass flow ... [more ▼]

Granular gravity driven flows of glass beads have been observed in a silo with a flat bottom. A dc high electric field has been applied perpendicularly to the silo to tune the cohesion. The outlet mass flow has been measured. An image subtraction technique has been applied to visualize the flow geometry and a spatiotemporal analysis of the flow dynamics has been performed. The outlet mass flow is independent of voltage, but a transition from funnel flow to rathole flow is observed. This transition is of probabilistic nature and an intermediate situation exists between the funnel and the rathole situations. At a given voltage, two kinds of flow dynamics can occur: a continuous flow or an intermittent flow. The electric field increases the probability to observe an intermittent flow. [less ▲]