Floating tracer clustering in divergent random flows modulated by an unsteady mesoscale ocean field

2020 ◽  
Vol 114 (4-5) ◽  
pp. 690-714
Author(s):  
Dmitry V. Stepanov ◽  
Eugene A. Ryzhov ◽  
Pavel Berloff ◽  
Konstantin V. Koshel
Keyword(s):  
2021 ◽  
Vol 103 (3) ◽  
Author(s):  
F. Sultanov ◽  
M. Sultanova ◽  
G. Falkovich ◽  
V. Lebedev ◽  
Y. Liu ◽  
...  
Keyword(s):  

1994 ◽  
Vol 49 (5) ◽  
pp. 4185-4191 ◽  
Author(s):  
G. Oshanin ◽  
A. Blumen

2018 ◽  
Vol 2018 ◽  
pp. 1-42 ◽  
Author(s):  
Xiaomeng Shi ◽  
Zhirui Ye ◽  
Nirajan Shiwakoti ◽  
Offer Grembek

Complex movement patterns of pedestrian traffic, ranging from unidirectional to multidirectional flows, are frequently observed in major public infrastructure such as transport hubs. These multidirectional movements can result in increased number of conflicts, thereby influencing the mobility and safety of pedestrian facilities. Therefore, empirical data collection on pedestrians’ complex movement has been on the rise in the past two decades. Although there are several reviews of mathematical simulation models for pedestrian traffic in the existing literature, a detailed review examining the challenges and opportunities on empirical studies on the pedestrians complex movements is limited in the literature. The overall aim of this study is to present a systematic review on the empirical data collection for uni- and multidirectional crowd complex movements. We first categorized the complex movements of pedestrian crowd into two general categories, namely, external governed movements and internal driven movements based on the interactions with the infrastructure and among pedestrians, respectively. Further, considering the hierarchy of movement complexity, we decomposed the externally governed movements of pedestrian traffic into several unique movement patterns including straight line, turning, egress and ingress, opposing, weaving, merging, diverging, and random flows. Analysis of the literature showed that empirical data were highly rich in straight line and egress flow while medium rich in turning, merging, weaving, and opposing flows, but poor in ingress, diverging, and random flows. We put emphasis on the need for the future global collaborative efforts on data sharing for the complex crowd movements.


Author(s):  
Vladimir V. Kalashnikov
Keyword(s):  

2018 ◽  
Vol 84 (4) ◽  
Author(s):  
I. Makarenko ◽  
P. Bushby ◽  
A. Fletcher ◽  
R. Henderson ◽  
N. Makarenko ◽  
...  

The predictions of mean-field electrodynamics can now be probed using direct numerical simulations of random flows and magnetic fields. When modelling astrophysical magnetohydrodynamics, it is important to verify that such simulations are in agreement with observations. One of the main challenges in this area is to identify robust quantitative measures to compare structures found in simulations with those inferred from astrophysical observations. A similar challenge is to compare quantitatively results from different simulations. Topological data analysis offers a range of techniques, including the Betti numbers and persistence diagrams, that can be used to facilitate such a comparison. After describing these tools, we first apply them to synthetic random fields and demonstrate that, when the data are standardized in a straightforward manner, some topological measures are insensitive to either large-scale trends or the resolution of the data. Focusing upon one particular astrophysical example, we apply topological data analysis to H iobservations of the turbulent interstellar medium (ISM) in the Milky Way and to recent magnetohydrodynamic simulations of the random, strongly compressible ISM. We stress that these topological techniques are generic and could be applied to any complex, multi-dimensional random field.


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