364 research outputs found
Lava Volume from Remote Sensing Data: Comparisons with Reverse Petrological Approaches for Two Types of Effusive Eruption
Synchronization in interacting Scale Free Networks
We study the fluctuations of the interface, in the steady state, of the
Surface Relaxation Model (SRM) in two scale free interacting networks where a
fraction of nodes in both networks interact one to one through external
connections. We find that as increases the fluctuations on both networks
decrease and thus the synchronization reaches an improvement of nearly
when . The decrease of the fluctuations on both networks is due mainly to
the diffusion through external connections which allows to reducing the load in
nodes by sending their excess mostly to low-degree nodes, which we report have
the lowest heights. This effect enhances the matching of the heights of low-and
high-degree nodes as increases reducing the fluctuations. This effect is
almost independent of the degree distribution of the networks which means that
the interconnection governs the behavior of the process over its topology.Comment: 13 pages, 7 figures. Added a relevant reference.Typos fixe
Diffusion on a lattice: transition rates, interactions and memory effects
We analyze diffusion of particles on a two dimensional square lattice. Each
lattice site contains an arbitrary number of particles. Interactions affect
particles only in the same site, and are macroscopically represented by the
excess chemical potential. In a recent work, a general expression for
transition rates between neighboring cells as functions of the excess chemical
potential was derived. With transition rates, the mean field tracer
diffusivity, , is immediately obtained. The tracer diffusivity, , contains the correlation factor , representing memory
effects. An analysis of the joint probability of having given numbers of
particles at different sites when a force is applied to a tagged particle
allows an approximate expression for to be derived. The expression is
applied to soft core interaction (different values for the maximum number of
particles in a site are considered) and extended hard core
Recovery of Interdependent Networks
Recent network research has focused on the cascading failures in a system of
interdependent networks and the necessary preconditions for system collapse. An
important question that has not been addressed is how to repair a failing
system before it suffers total breakdown. Here we introduce a recovery strategy
of nodes and develop an analytic and numerical framework for studying the
concurrent failure and recovery of a system of interdependent networks based on
an efficient and practically reasonable strategy. Our strategy consists of
repairing a fraction of failed nodes, with probability of recovery ,
that are neighbors of the largest connected component of each constituent
network. We find that, for a given initial failure of a fraction of
nodes, there is a critical probability of recovery above which the cascade is
halted and the system fully restores to its initial state and below which the
system abruptly collapses. As a consequence we find in the plane of
the phase diagram three distinct phases. A phase in which the system never
collapses without being restored, another phase in which the recovery strategy
avoids the breakdown, and a phase in which even the repairing process cannot
avoid the system collapse
Reversible bootstrap percolation: Fake news and fact checking
Bootstrap percolation has been used to describe opinion formation in society
and other social and natural phenomena. The formal equation of the bootstrap
percolation may have more than one solution, corresponding to several stable
fixed points of the corresponding iteration process. We construct a reversible
bootstrap percolation process, which converges to these extra solutions
displaying a hysteresis typical of discontinuous phase transitions. This
process provides a reasonable model for fake news spreading and the
effectiveness of fact checking. We show that sometimes it is not sufficient to
discard all the sources of fake news in order to reverse the belief of a
population that formed under the influence of these sources
Synchronization in Scale Free networks: The role of finite size effects
Synchronization problems in complex networks are very often studied by
researchers due to its many applications to various fields such as
neurobiology, e-commerce and completion of tasks. In particular, Scale Free
networks with degree distribution , are widely used in
research since they are ubiquitous in nature and other real systems. In this
paper we focus on the surface relaxation growth model in Scale Free networks
with , and study the scaling behavior of the fluctuations, in
the steady state, with the system size . We find a novel behavior of the
fluctuations characterized by a crossover between two regimes at a value of
that depends on : a logarithmic regime, found in previous
research, and a constant regime. We propose a function that describes this
crossover, which is in very good agreement with the simulations. We also find
that, for a system size above , the fluctuations decrease with
, which means that the synchronization of the system improves as
increases. We explain this crossover analyzing the role of the
network's heterogeneity produced by the system size and the exponent of the
degree distribution.Comment: 9 pages and 5 figures. Accepted in Europhysics Letter
Design and Experimental Characterization of EDFA Based WDM Ring Networks with Free ASE Light Re-circulation and Link Control for Network Survivability
In this paper, we theoretically and experimentally investigate the performance of erbium-doped fiber amplifier (EDFA)-based WDM ring networks with free amplified spontaneous emission (ASE) light recirculation. We show that, with proper network and amplifier design, the lasing light generated by free ASE recirculation within the looped network provides an effective gain clamping technique, ensuring limited signal power excursions under WDM channels add-drop operations.
Considering a ring network composed of eight fiber sections and eight EDFAs, maximum signal power overshoots below 2.5 dB have been measured under 23 24 WDM channels drop. Optical signal-to-noise ratio (OSNR) analysis and bit-error rate (BER) measurement at 10 Gb/s confirm acceptable performances and negligible penalties due to polarization effects and relative intensity noise transfer from laser light to WDM signals. We also propose and demonstrate a new link control technique which overcomes the main limiting factors of such networks, respectively, related to OSNR degradation, stability and survivability to fiber and EDFA breakages
Equilibrium Viscosity and Disequilibrium Rheology of a high Magnesium Basalt from Piton De La Fournaise volcano, La Reunion, Indian Ocean, France
Lava flows are a common hazard at basaltic to intermediate volcanoes and have posed a significant threat to La Reunion Island over the past centuries. In sustained flow units, the efficiency of lava transport away from the vent is dominated by cooling. For basaltic to intermediate lavas, it is the ability of the lava to solidify during cooling which exerts a first-order control on spatial extent and flow distance. As a consequence, understanding the sub-liquidus rheology of lavas has become a key focus in lava flow research in the past decade. To date, the development of a systematic understanding of lava rheology during emplacement conditions has been significantly hampered by a lack of experimental data. Here we present new data on the rheological evolution of crystallizing high-Mg basalt from Piton de la Fournaise. Sub-liquidus experiments were performed at constant cooling rates ranging from 0.5 to 5 K/min. Those rates mimic thermal conditions experienced 1) by lava during flow on the surface and 2) by magma during dike and sill emplacement. Our data show that the effective viscosity of the crystallizing suspension increases until reaching a specific sub-liquidus temperature, the so-called "rheological cutoff temperature" (T-cutoff), at which the lava becomes rheologically immobile and flow ceases. This departure from the pure liquid viscosity curve to higher viscosity is a consequence of rapid crystallization and its variability for a given lava is found to be primarily controlled by the imposed cooling rate. Based on these experimental data, we adapt the failure forecasting method (FFM) - commonly used to describe the self- accelerating nature of seismic signals to forecast material failure - to predict the rheological cut-off temperature (T-cutoff). The presented data substantially expand the modest experimental database on non-equilibrium rheology of lavas and represent a step towards understanding the underlying process dynamics
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