Conditional exponents, entropies and a measure of dynamical self-organization

In dynamical systems composed of interacting parts, conditional exponents, conditional exponent entropies and cylindrical entropies are shown to be well defined ergodic invariants which characterize the dynamical selforganization and statitical independence of the constituent parts. An example of interacting Bernoulli units is used to illustrate the nature of these invariants.Comment: 6 pages Latex, 1 black and white and 2 color figures, replacement of damaged gif file

Synchronization time in a hyperbolic dynamical system with long-range interactions

We show that the threshold of complete synchronization in a lattice of coupled non-smooth chaotic maps is determined by linear stability along the directions transversal to the synchronization subspace. We examine carefully the sychronization time and show that a inadequate observation of the system evolution leads to wrong results. We present both careful numerical experiments and a rigorous mathematical explanation confirming this fact, allowing for a generalization involving hyperbolic coupled map lattices.Comment: 22 pages (preprint format), 4 figures - accepted for publication in Physica A (June 28, 2010

Stability of Synchronized Chaos in Coupled Dynamical Systems

We consider the stability of synchronized chaos in coupled map lattices and in coupled ordinary differential equations. Applying the theory of Hermitian and positive semidefinite matrices we prove two results that give simple bounds on coupling strengths which ensure the stability of synchronized chaos. Previous results in this area involving particular coupling schemes (e.g. global coupling and nearest neighbor diffusive coupling) are included as special cases of the present work.Comment: 9 page

Network synchronization: Spectral versus statistical properties

We consider synchronization of weighted networks, possibly with asymmetrical connections. We show that the synchronizability of the networks cannot be directly inferred from their statistical properties. Small local changes in the network structure can sensitively affect the eigenvalues relevant for synchronization, while the gross statistical network properties remain essentially unchanged. Consequently, commonly used statistical properties, including the degree distribution, degree homogeneity, average degree, average distance, degree correlation, and clustering coefficient, can fail to characterize the synchronizability of networks

A Software Suite for the Control and the Monitoring of Adaptive Robotic Ecologies

Adaptive robotic ecologies are networks of heterogeneous robotic devices (sensors, actuators, automated appliances) pervasively embedded in everyday environments, where they learn to cooperate towards the achievement of complex tasks. While their flexibility makes them an increasingly popular way to improve a system’s reliability, scalability, robustness and autonomy, their effective realisation demands integrated control and software solutions for the specification, integration and management of their highly heterogeneous and computational constrained components. In this extended abstract we briefly illustrate the characteristic requirements dictated by robotic ecologies, discuss our experience in developing adaptive robotic ecologies, and provide an overview of the specific solutions developed as part of the EU FP7 RUBICON Project

The Black Ranger

In lieu of an abstract, below is the essay\u27s first paragraph. The kid just doesn\u27t seem to understand that turning on a light switch won\u27t hurt him! Little Bobby used to love to run around the house playing swords with his older brother. Bobby and his brother used to take the cardboard cylinder tubes out of the paper towel rolls to bash each other on their heads. However, as Bobby\u27s older brother reached his adolescent years, Bobby was left to play alone, for Bobby\u27s older brother was no longer interested in Bobby\u27s level of play. But Bobby always loved playing with objects that could resemble a sword! A pencil, a twig, a butter knife

Finite Element Simulation of Large-Scale Confined Inflatable Structures

The protection of transportation tunnels is one of the top priorities of transportation and government entities. Transportation tunnels have been identified as particularly vulnerable to different threats such as propagation of toxic gasses, or smoke originated by human activities or flooding originated by extreme climatic events such as hurricanes and severe weather. Finding solutions to minimize the consequences of disastrous events has become critical to increase the resiliency of tunnel systems. The implementation of large-scale inflatable structures at specific locations of the tunnel system for containing the propagation of flooding or gases is now possible. When a threat happens, a sensing system detects the threat and triggers the activation of an inflation system which can deploy, inflate and pressurize the inflatable structure in a few minutes. When the inflatable structure is completely inflated, it acts as a barrier that can isolate the compromised region and contain the threat. The feasibility of this concept was demonstrated in 2008, and several experimental evaluations were conducted in the recent years to demonstrate the operational viability of this solution. Despite the successful results seen in the experimental evaluations, the development of simulations that can predict results in advance to reduce the number of experimental iterations is still essential. Finite Element simulation efforts performed in the recent years contributed to the understanding of the dynamics of the deployment and inflation of an inflatable structure for one particular tunnel profile and one folding and deployment configuration. However, if the membrane material of the inflatable changes, or the shape or configuration of the tunnel profile changes, or the position for storage of the folded inflatable changes, the initial behavior of the unstressed membrane during the initial deployment and later inflation, will be different. All this variability increases the need of experimental iterations to determine the appropriate combination of parameters to achieve acceptable results. Considering that the resources for experimental iterations can be very limited, there is a clear need to continue with the development of predictive models that can account for the different factors involved in the implementation of inflatable structures for tunnel protection.;This work presents the development of Finite Element simulations generated for the evaluation of different phases of the operation of a large-scale inflatable structure used for sealing a tunnel segment. The simulations developed in this work focused on reproducing deflation, folding, and placement procedures for deploying an inflatable from the ceiling of a tunnel segment. The models were also used to evaluate the behavior of the inflatable during the initial deployment and the full inflation. Different strategies were analyzed with the ultimate goal of maximizing the global and local conformity, which translate in a better sealing capacity of the inflatable to the tunnel profile. The results of the simulations showed that a very flat shape can be achieved by implementing a controlled deflation of the nominal shape of the inflatable as a starting point of the folding procedures. Moreover, a combination of translational and rotational planes allowed the flattened shape to reach a more compact shape at the end of the folding procedures. Simulation results also showed that the stiffness of the membrane influenced the shape and behavior of the inflatable during the initial deployment. Moreover, results demonstrated that the implementation of passive restrainers to control the movement and release of the membrane during the deflation, folding, deployment and inflation contributed to reach higher levels of local conformity of the inflatable to the tunnel perimeter, as well as an increase of the contact area as the global and local conformity improved. A comparison of simulation results with available experimental data demonstrated a good level of agreement between the finite element simulations and the experimental observations