Conditional Spatial Patterning: Beyond the Nearest Neighbor

1987 ◽  
Vol 52 (3) ◽  
pp. 500-521 ◽  
Author(s):  
Albertus Voorrips ◽  
John M. O'Shea
Keyword(s):  
Computer Simulation ◽  
Spatial Autocorrelation ◽  
Nearest Neighbor ◽  
Spatial Patterning ◽  
Late Mesolithic ◽  
Count Statistic

This paper discusses a method for the analysis of spatial patterning which is based on aspects of the study of spatial autocorrelation. By means of computer simulation it is shown that the join count statistic (Cliff and Ord 1973; Moran 1950) has a wider validity than was presumed originally. Some archaeological applications from the analysis of a late Mesolithic cemetery in Karelia, USSR, are presented.

Analisis Pola Kebakaran Lahan di Kalimantan Timur dengan MODIS dan VIIRS

2020 ◽  
Vol 21 (1) ◽  
pp. 84
Author(s):  
Aditya Pranata Wibowo ◽  
Frederik Samuel Papilaya
Keyword(s):  
Spatial Autocorrelation ◽  
Nearest Neighbor ◽  
Directional Distribution

Kebakaran adalah suatu peristiwa timbulnya reaksi oksidasi saat adanya bahan bakar, oksigen, dan energi panas yang menyebabkan pembakaran yg tidak terkendali dan menyebabkan kerugian. Pemantauan secara spasial terhadap kebakaran menjadi suatu hal yang sangat penting untuk dikaji. Penelitian ini bertujuan untuk mengetahui daerah manakah yang paling banyak mengalami kebakaran dan juga pola dari kebakaran tersebut. Sumber data didapatkan dari website FIRMS yang merupakan data yang bersifat kuantitatif dan data primer. Metode analisis yang digunakan adalah metode analisis Spatial Autocorrelation, Average Nearest Neighbor, Optimized Hotspot, Directional Distribution (Standard Devitional Ellipse), dan Temporal Collect Event. Hasil yang telah didapatkan dari analisis bermetode Directional Distribution, Optimized Hotspot, dan Temporal Collect Event adalah terdapat banyak titik api yang berada di Kecamatan Kutai Kartanegara, Kutai Barat, Kutai Timur, Berau, dan Paser. Dalam analisis Spatial Autocorrelation ditemukan bahwa terdapat korelasi antara lokasi terjadinya titik api dan ukuran sejati dari titik api. Analisis Average Nearest Neighbor menunjukkan bahwa titik api terkumpul pada beberapa tempat dan tidak tersebar merata.

Computer simulation of phase transitions of the Heisenberg antiferromagnetic model

2019 ◽  
pp. 25-31
Author(s):  
M.K. Ramazanov ◽  
A.K. Murtazaev
Keyword(s):  
Computer Simulation ◽  
Phase Transitions ◽  
Nearest Neighbor ◽  
Three Dimensional ◽  
Exchange Interactions ◽  
Nearest Neighbors ◽  
Neighbor Interaction ◽  
A Value ◽  
The Monte Carlo Method ◽  
Antiferromagnetic Model

Based on the replica algorithm by the Monte Carlo method, a computer simulation of the three-dimensional antiferromagnetic Heisenberg model is performed, taking into account the interactions of the first and second nearest neighbors. The phase transitions of this model are studied. The investigations were carried out for the ratios of the exchange interactions of the first and second nearest neighbors $r = J_2 / J_1$ in the range $0.0 \leq r \leq 1.0$. The phase diagram of the critical temperature dependence on a value of the next-nearest neighbor interaction is plotted.

scholarly journals Spatial and Spatiotemporal Pattern Analysis of Coconut Lethal Yellowing in Mozambique

2010 ◽  
Vol 100 (4) ◽  
pp. 300-312 ◽  
Author(s):  
F. Bonnot ◽  
H. de Franqueville ◽  
E. Lourenço
Keyword(s):  
Spatial Autocorrelation ◽  
Pattern Analysis ◽  
Disease Incidence ◽  
Spatiotemporal Pattern ◽  
Major Threat ◽  
Coconut Tree ◽  
Permutation Methods ◽  
Lethal Yellowing ◽  
Count Statistic ◽  
Specific Distance

Coconut lethal yellowing (LY) is caused by a phytoplasma and is a major threat for coconut production throughout its growing area. Incidence of LY was monitored visually on every coconut tree in six fields in Mozambique for 34 months. Disease progress curves were plotted and average monthly disease incidence was estimated. Spatial patterns of disease incidence were analyzed at six assessment times. Aggregation was tested by the coefficient of spatial autocorrelation of the β-binomial distribution of diseased trees in quadrats. The binary power law was used as an assessment of overdispersion across the six fields. Spatial autocorrelation between symptomatic trees was measured by the BB join count statistic based on the number of pairs of diseased trees separated by a specific distance and orientation, and tested using permutation methods. Aggregation of symptomatic trees was detected in every field in both cumulative and new cases. Spatiotemporal patterns were analyzed with two methods. The proximity of symptomatic trees at two assessment times was investigated using the spatiotemporal BB join count statistic based on the number of pairs of trees separated by a specific distance and orientation and exhibiting the first symptoms of LY at the two times. The semivariogram of times of appearance of LY was calculated to characterize how the lag between times of appearance of LY was related to the distance between symptomatic trees. Both statistics were tested using permutation methods. A tendency for new cases to appear in the proximity of previously diseased trees and a spatially structured pattern of times of appearance of LY within clusters of diseased trees were detected, suggesting secondary spread of the disease.

3DAP Analysis and Computer Simulation of Nanocluster Formation in the Initial Aging Stage of Al-Zn Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 437-442 ◽  
Author(s):  
Yoshiki Komiya ◽  
Shoichi Hirosawa ◽  
Tatsuo Sato
Keyword(s):  
Computer Simulation ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Nearest Neighbor ◽  
Interaction Model ◽  
Atomic Scale ◽  
Many Body ◽  
Many Body Interactions ◽  
Aging Stage ◽  
Zn Alloys

The formation of nanoclusters in the early aging stage is not fully clarified due to their extremely small sizes. To clarify the atomic-scale clustering of solute atoms, a three-dimensional atom probe (3DAP) analysis and a Monte Carlo computer simulation have been conducted together for Al-Zn alloys. The nanoclusters in the alloy aged at room temperature were successfully detected in the obtained 3DAP maps. From these maps the growth behavior of nanoclusters during aging was experimentally examined. In the Monte Carlo simulation, on the other hand, many-body nearest neighbor interactions between atoms and between atoms and a vacancy were taken into account. The Zn concentration of the clusters calculated in the 4-body interaction model best agreed with that obtained experimentally, suggesting the importance of many-body interactions. Therefore, it was confirmed that the combined analysis of 3DAP and the well-constructed Monte Carlo simulation is useful to make clear the nanocluster formation in alloys.

Observation of Superlattice Dislocations on Cube Planes in Ni3Al

1973 ◽  
Vol 31 ◽  
pp. 174-175 ◽  
Author(s):  
J. M. Oblak ◽  
W. H. Rand
Keyword(s):  
Nearest Neighbor ◽  
Antiphase Boundary ◽  
Nearest Neighbors ◽  
High Energy ◽  
Cross Slip ◽  
Octahedral Plane ◽  
Trapping Mechanism ◽  
Slip Traces

The energy of an a/2 <110> shear antiphase. boundary in the Ll2 expected to be at a minimum on {100} cube planes because here strue ture is there is no violation of nearest-neighbor order. The latter however does involve the disruption of second nearest neighbors. It has been suggested that cross slip of paired a/2 <110> dislocations from octahedral onto cube planes is an important dislocation trapping mechanism in Ni3Al; furthermore, slip traces consistent with cube slip are observed above 920°K.Due to the high energy of the {111} antiphase boundary (> 200 mJ/m2), paired a/2 <110> dislocations are tightly constricted on the octahedral plane and cannot be individually resolved.

Application of Lattice Imaging Techniques to Amorphous Films

1975 ◽  
Vol 33 ◽  
pp. 8-9
Author(s):  
S. R. Herd ◽  
P. Chaudhari
Keyword(s):  
Nearest Neighbor ◽  
Random Network ◽  
Imaging Techniques ◽  
Network Models ◽  
Accurate Method ◽  
Direct Transmission ◽  
Lattice Imaging ◽  
Transmission Electron ◽  
Lattice Planes ◽  
Nearest Neighbor Distances

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.

Characterization of Modulated Structure Through Structure Images and their Computer Simulation

1990 ◽  
Vol 48 (1) ◽  
pp. 70-71
Author(s):  
Kiyomichi Nakai ◽  
Yusuke Isobe ◽  
Chiken Kinoshita ◽  
Kazutoshi Shinohara
Keyword(s):  
Computer Simulation ◽  
High Resolution ◽  
Spherical Aberration ◽  
High Resolution Electron Microscopy ◽  
Basic Mechanism ◽  
Objective Lens ◽  
Specimen Thickness ◽  
Transmitted Beam ◽  
Modulated Structure ◽  
Resolution Electron

Induced spinodal decomposition under electron irradiation in a Ni-Au alloy has been investigated with respect to its basic mechanism and confirmed to be caused by the relaxation of coherent strain associated with modulated structure. Modulation of white-dots on structure images of modulated structure due to high-resolution electron microscopy is reduced with irradiation. In this paper the atom arrangement of the modulated structure is confirmed with computer simulation on the structure images, and the relaxation of the coherent strain is concluded to be due to the reduction of phase-modulation.Structure images of three-dimensional modulated structure along <100> were taken with the JEM-4000EX high-resolution electron microscope at the HVEM Laboratory, Kyushu University. The transmitted beam and four 200 reflections with their satellites from the modulated structure in an fee Ni-30.0at%Au alloy under illumination of 400keV electrons were used for the structure images under a condition of the spherical aberration constant of the objective lens, Cs = 1mm, the divergence of the beam, α = 3 × 10-4 rad, underfocus, Δf ≃ -50nm and specimen thickness, t ≃ 15nm. The CIHRTEM code was used for the simulation of the structure image.

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