scholarly journals Role of packing density and spatial correlations in strongly scattering 3D systems

Optica ◽  
2018 ◽  
Vol 5 (9) ◽  
pp. 1037 ◽  
Author(s):  
Lorenzo Pattelli ◽  
Amos Egel ◽  
Uli Lemmer ◽  
Diederik S. Wiersma
Keyword(s):  
Packing Density ◽  
Spatial Correlations

Spatial Correlations in CyberShake Physics‐Based Ground‐Motion Simulations

2019 ◽  
Vol 109 (6) ◽  
pp. 2447-2458 ◽  
Author(s):  
Yilin Chen ◽  
Jack W. Baker
Keyword(s):  
Ground Motion ◽  
Prediction Models ◽  
Spatial Correlations ◽  
Ground Motion Simulation ◽  
Source Effects ◽  
Simulation Validation ◽  
Geological Conditions ◽  
Simulated Ground Motions ◽  
Strong Ground

Abstract When studying the performance of distributed infrastructure in earthquakes, spatial variations in strong ground motion have a significant impact. Currently, prediction models for spatial ground‐motion variations in future earthquakes are calibrated using ground‐motion observations from densely recorded earthquakes. Although useful, that calibration process requires strong assumptions about stationarity and isotropy of correlations. This article reports results from conducting analogous spatial variation estimation using physics‐based simulations from the CyberShake platform. This platform contains simulated ground motions from hundreds of thousands of rupture realizations, at locations throughout southern California, providing a synthetic ground‐motion catalog that is much richer than we could ever hope to achieve from recordings. That richness allows significant relaxation of stationarity and isotropy assumptions, and provides new insights regarding the role of source and path heterogeneity on the spatial correlation of ground‐motion amplitudes. The results suggest that geological conditions, source effects, and path effects have significant impacts on spatial correlations. In addition, this work serves as a new dimension of ground‐motion simulation validation, because the estimated correlations can be compared to results from past earthquakes.

scholarly journals ROLE OF THE COLORED NOISE IN SPATIO-TEMPORAL BEHAVIOR OF TWO COMPETING SPECIES

2005 ◽  
Vol 05 (02) ◽  
pp. L337-L342 ◽  
Author(s):  
D. VALENTI ◽  
A. FIASCONARO ◽  
B. SPAGNOLO
Keyword(s):  
Noise Intensity ◽  
Large Scale ◽  
Colored Noise ◽  
Spatial Distributions ◽  
Temporal Behavior ◽  
Spatial Correlations ◽  
Interacting Species ◽  
Spatio Temporal ◽  
Nonmonotonic Behavior

We study the spatial distributions of two randomly interacting species, in the presence of an external multiplicative colored noise. The dynamics of the ecosystem is described by a coupled map lattice model. We find a nonmonotonic behavior in the formation of large scale spatial correlations as a function of the multiplicative colored noise intensity. This behavior is shifted towards higher values of the noise intensity for increasing correlation time of the noise.

scholarly journals Deforestation Hotspots in the Brazilian Amazon: Evidence and Causes as Assessed from Remote Sensing and Census Data

2007 ◽  
Vol 11 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Nilson Clementino Ferreira ◽  
Laerte Guimarães Ferreira ◽  
Fausto Miziara
Keyword(s):  
Remote Sensing ◽  
Census Data ◽  
Brazilian Amazon ◽  
The Other ◽  
Spatial Correlations ◽  
Institutional Integration ◽  
Federal Level ◽  
Critical Areas ◽  
Rapid Pace

Abstract The main goal of this study, conducted in an area comprising 221 municipalities, in which 90% of the deforestation in the Legal Amazon takes place, was to understand the role of the agrarian structure in the conversion of forest into pasture and agriculture fields. Linear regression results indicate that 54%–62% of the variation in deforestation occurred between 1997 and 2004, respectively, and are explained as a function of changes in the amount of appropriated land in 1995. Likewise, up to 80% of the deforestation can be well explained by the variation in land concentration. In fact, strong spatial correlations were found between deforestation hotspots and land appropriation and land concentration. On the other hand, these critical areas have insufficient governance, particularly at the federal level. As the results of this study clearly demonstrate, strong governance and institutional integration, with emphasis on the territorial ordainment, are mandatory in order to reduce the rapid pace of deforestation in the Brazilian Amazon.

scholarly journals Honest and cheating strategies in a simple model of aggressive communication: the role of spatial correlations

2018 ◽  
Author(s):  
Szabolcs Számadó ◽  
András Szántó
Keyword(s):  
Simple Game ◽  
Theoretical Models ◽  
Spatially Explicit ◽  
Extensive Literature ◽  
Spatial Correlations ◽  
Cooperative Strategies ◽  
Aggressive Communication ◽  
Evolution Of Communication ◽  
Traditional Game

AbstractThe evolution and maintenance of communication in terms of aggressive interactions is a long-debated issue. Several game theoretical models and individual based computer simulations investigated this problem in terms of a simple game of aggressive communication. So far all of these investigations focused on well mixed population of individuals. However, spatial correlations can emerge in nature where individuals or group of individuals defend resources. The extensive literature on cooperative games show that these spatial correlations can be vital in the maintenance and evolution of cooperative strategies, thus it is reasonable to expect that such correlations could play an important role in the evolution of honest communication as well. Here we investigate a traditional game of aggressive communication in a spatially explicit context. We investigate the role of spatial correlations by comparing results of evolvability in well mixed populations with results from spatially explicit populations. Spatial correlations seem to inhibit the evolution of communication in the spatially explicit version of this game. This result is unexpected, and it requires further investigation to understand.

scholarly journals Fractal Generalization of the Scher–Montroll Model for Anomalous Transit-Time Dispersion in Disordered Solids

Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1991
Author(s):  
Renat T. Sibatov
Keyword(s):  
Transit Time ◽  
Time Of Flight ◽  
Fractal Model ◽  
Localized States ◽  
Spatial Correlations ◽  
Dispersive Transport ◽  
Disordered Solids ◽  
Time Dispersion ◽  
Longitudinal Coordinate

The Scher–Montroll model successfully describes subdiffusive photocurrents in homogeneously disordered semiconductors. The present paper generalizes this model to the case of fractal spatial disorder (self-similar random distribution of localized states) under the conditions of the time-of-flight experiment. Within the fractal model, we calculate charge carrier densities and transient current for different cases, solving the corresponding fractional-order equations of dispersive transport. Photocurrent response after injection of non-equilibrium carriers by the short laser pulse is expressed via fractional stable distributions. For the simplest case of one-sided instantaneous jumps (tunneling) between neighboring localized states, the dispersive transport equation contains fractional Riemann–Liouville derivatives on time and longitudinal coordinate. We discuss the role of back-scattering, spatial correlations induced by quenching of disorder, and spatiotemporal non-locality produced by the fractal trap distribution and the finite velocity of motion between localized states. We derive expressions for the photocurrent and transit time that allow us to determine the fractal dimension of the distribution of traps and the dispersion parameter from the time-of-flight measurements.

Spatial Correlations in SMOS Antenna: The Role of Effective Point Spread Functions

2016 ◽  
Vol 54 (8) ◽  
pp. 4906-4916
Author(s):  
Justino Martinez ◽  
Antonio Turiel ◽  
Veronica Gonzalez-Gambau ◽  
Estrella Olmedo
Keyword(s):  
Spatial Correlations ◽  
Point Spread Functions ◽  
Point Spread

Special Features of Network Formation by Chain Crosslinking Copolymerization

1993 ◽  
Vol 58 (10) ◽  
pp. 2245-2265 ◽  
Author(s):  
Karel Dušek
Keyword(s):  
Network Formation ◽  
Double Bonds ◽  
Spatial Correlations ◽  
Phase Separations ◽  
Network Chain ◽  
Gel Phase ◽  
Chain Conformations ◽  
Theoretical Simulations ◽  
Steric Hindrances

Special features of free-radical crosslinking copolymerization and the structure of the resulting products have been reviewed. Characteristic is the effect of spatial correlations on the apparent reactivity of pendant double bonds. These correlation make the apparent reactivity in the course of copolymerization to increase (cyclization) and decrease (steric hindrances). At intermediate and higher concentrations of the crosslinker, compact structures are formed which are internally crosslinked. Only pendant double bonds in the peripheral layer are able to take part in polymerization reactions whereas the internal ones cannot react. The state of theoretical simulations of this structure growth is discussed with a special emphasis on the development of the kinetic (coagulation) network formation theories so that the above mentioned features may be taken into account. Also, the important role of the presence of a diluent during polymerization id discussed. It can result in a change of network chain conformations necessary for networks exhibiting volume phase transitions. Alternatively, it can induce liquid-gel phase separations resulting in inhomogeneous networks having a variety of morphologies.

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