The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform
Samuel A Cushman - One of the best experts on this subject based on the ideXlab platform.
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Surface metrics: an alternative to patch metrics for the quantification of landscape structure
Landscape Ecology, 2009Co-Authors: Kevin Mcgarigal, Sermin Tagil, Samuel A CushmanAbstract:Modern landscape ecology is based on the patch mosaic paradigm, in which landscapes are conceptualized and analyzed as mosaics of discrete patches. While this model has been widely successful, there are many situations where it is more meaningful to model landscape structure based on continuous rather than discrete spatial heterogeneity. The growing field of Surface metrology offers a variety of Surface metrics for quantifying landscape gradients, yet these metrics are largely unknown and/or unused by landscape ecologists. In this paper, we describe a suite of Surface metrics with potential for landscape ecological application. We assessed the redundancy among metrics and sought to find groups of similarly behaved metrics by examining metric performance across 264 sample landscapes in western Turkey. For comparative purposes and to evaluate the robustness of the observed patterns, we examined 16 different patch mosaic models and 18 different landscape gradient models of landscape structure. Surface metrics were highly redundant, but less so than patch metrics, and consistently aggregated into four cohesive clusters of similarly behaved metrics representing Surface roughness, shape of the Surface Height Distribution, and angular and radial Surface texture. While the Surface roughness metrics have strong analogs among the patch metrics, the other Surface components are largely unique to landscape gradients. We contend that the Surface properties we identified are nearly universal and have potential to offer new insights into landscape pattern–process relationships.
Kevin Mcgarigal - One of the best experts on this subject based on the ideXlab platform.
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Surface metrics: an alternative to patch metrics for the quantification of landscape structure
Landscape Ecology, 2009Co-Authors: Kevin Mcgarigal, Sermin Tagil, Samuel A CushmanAbstract:Modern landscape ecology is based on the patch mosaic paradigm, in which landscapes are conceptualized and analyzed as mosaics of discrete patches. While this model has been widely successful, there are many situations where it is more meaningful to model landscape structure based on continuous rather than discrete spatial heterogeneity. The growing field of Surface metrology offers a variety of Surface metrics for quantifying landscape gradients, yet these metrics are largely unknown and/or unused by landscape ecologists. In this paper, we describe a suite of Surface metrics with potential for landscape ecological application. We assessed the redundancy among metrics and sought to find groups of similarly behaved metrics by examining metric performance across 264 sample landscapes in western Turkey. For comparative purposes and to evaluate the robustness of the observed patterns, we examined 16 different patch mosaic models and 18 different landscape gradient models of landscape structure. Surface metrics were highly redundant, but less so than patch metrics, and consistently aggregated into four cohesive clusters of similarly behaved metrics representing Surface roughness, shape of the Surface Height Distribution, and angular and radial Surface texture. While the Surface roughness metrics have strong analogs among the patch metrics, the other Surface components are largely unique to landscape gradients. We contend that the Surface properties we identified are nearly universal and have potential to offer new insights into landscape pattern–process relationships.
Vladimir I Trofimov - One of the best experts on this subject based on the ideXlab platform.
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quantitative characterization of the mesoscopic Surface roughness in a growing island film
Computational Materials Science, 2005Co-Authors: Vladimir I Trofimov, Ilya V Trofimov, Jongil KimAbstract:A quantitative description of mesoscopic Surface roughness generated in thin film growing via 3D island mechanism is presented. Analysis is based on the statistical model of a random nucleation and growth of hemispherical islands accounting for their collisions at late stages. Analytical expressions for a number of Surface relief parameters: the rms roughness, the roughness coefficient, the Surface Height (depth) Distribution and the package density factor providing a rather complete quantitative description of the evolving Surface morphology during growth process in different condensation regimes are derived. It is shown that the Surface Height Distribution is a non-Gaussian with a negative skewness and that the rms roughness and the roughness coefficient kinetics can be represented as a universal (independent of a condensation regime) unimodal function of either coverage or film thickness with a maximum just prior the completed film formation. The non-monotonic Surface roughness dynamics in a growth process predicted by the model is consistent with experimental data.
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quantitative description of Surface morphology evolution in a growing film
Applied Surface Science, 2003Co-Authors: Vladimir I Trofimov, Hee Seok ParkAbstract:Abstract A quantitative description of the Surface morphology evolution in thin film growing via 3D island mechanism is presented. The treatment is based on the calculation of the survival probability for any point on (or above) a substrate during growth process. The paraboloid growth model is considered. In this model, the lateral growth of an island occurs in a circle form via capture of migrating adatoms, while its vertical growth proceeds at constant velocity owing to direct impingement of deposited atoms, so that a steady (in time) and random (in space) Surface relief consisting of paraboloid growth hillocks is developed eventually. For this Surface relief, forming at paraboloid growth, the Height–Height autocorrelation function is derived for different hillock shape and different nucleation mode generating different hillock space Distribution. It is found that the hillock shape strongly affects on the overall Surface roughness and the hillock space Distribution influences on both the autocorrelation function form and the rms roughness. The Surface Height Distribution is asymmetric, non-Gaussian with negative skewness. The random rough Surface of thin film with surely non-Gaussian Height Distribution is characterized by close-to-Gaussian Height–Height correlation function.
Sermin Tagil - One of the best experts on this subject based on the ideXlab platform.
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Surface metrics: an alternative to patch metrics for the quantification of landscape structure
Landscape Ecology, 2009Co-Authors: Kevin Mcgarigal, Sermin Tagil, Samuel A CushmanAbstract:Modern landscape ecology is based on the patch mosaic paradigm, in which landscapes are conceptualized and analyzed as mosaics of discrete patches. While this model has been widely successful, there are many situations where it is more meaningful to model landscape structure based on continuous rather than discrete spatial heterogeneity. The growing field of Surface metrology offers a variety of Surface metrics for quantifying landscape gradients, yet these metrics are largely unknown and/or unused by landscape ecologists. In this paper, we describe a suite of Surface metrics with potential for landscape ecological application. We assessed the redundancy among metrics and sought to find groups of similarly behaved metrics by examining metric performance across 264 sample landscapes in western Turkey. For comparative purposes and to evaluate the robustness of the observed patterns, we examined 16 different patch mosaic models and 18 different landscape gradient models of landscape structure. Surface metrics were highly redundant, but less so than patch metrics, and consistently aggregated into four cohesive clusters of similarly behaved metrics representing Surface roughness, shape of the Surface Height Distribution, and angular and radial Surface texture. While the Surface roughness metrics have strong analogs among the patch metrics, the other Surface components are largely unique to landscape gradients. We contend that the Surface properties we identified are nearly universal and have potential to offer new insights into landscape pattern–process relationships.
Jan H Rakels - One of the best experts on this subject based on the ideXlab platform.
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influence of the Surface Height Distribution on the total integrated scatter tis formula
Nanotechnology, 1996Co-Authors: Jan H RakelsAbstract:The TIS formula, relating the rms Surface roughness parameter to the specularly reflected light by , has been derived for Surfaces with a Gaussian Height Distribution. This study investigates the validity of this formula for various realistic and artificial Surface Height Distributions with and without skewness. The specular light intensity is calculated by using a Fourier transform expression for the Kirchhoff formalism of diffraction. The Kirchhoff formalism is valid for gently sloped metallic Surfaces producing small scattering angles. In the case where the scattered light is collected by a lens, the light Distribution in the focal plane of this lens is proportional to the power spectrum of the optical field close to the scattering Surface. This optical input field can be related to the Surface Height Distribution by geometrical optics, resulting in a phase modulation expression for the input field where and y(x) is the Surface profile. Normal incidence illumination with wavelength is assumed in this study. The theoretical Surface profiles under investigation can be divided into profiles with and without skewness. They have the following Surface Height Distributions: (i) zero skewness (can be produced by grinding triangular profile diffraction grating), exponential, Gaussian, uniform, sinusoidal, square wave; (ii) non-zero skewness (can be produced by diamond turning split triangular profile resembling plateau honing): parabolic cusp, pseudo-uniform. The results of this study are: (i) in the Surface roughness range the percentage error in the roughness value obtained by the TIS formula is limited to 10% and (ii) skewness in the Surface Height Distribution tends to reduce the light scatter for a given Surface roughness.