scholarly journals Scale-free gravitational collapse as the origin of ρ ∼ r−2 density profile – a possible role of turbulence in regulating gravitational collapse

2018 ◽  
Vol 477 (4) ◽  
pp. 4951-4956 ◽  
Author(s):  
Guang-Xing Li
2014 ◽  
Vol 563 ◽  
pp. A85 ◽  
Author(s):  
Neil Vaytet ◽  
Kengo Tomida ◽  
Gilles Chabrier

2018 ◽  
Vol 68 (5) ◽  
pp. 563-569
Author(s):  
Meesoon HA*

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Khaldoun Khashanah ◽  
Talal Alsulaiman

We propose a metamodel to assess simulated market stability by introducing information connectivity in an agent-based network. The market is occupied by heterogeneous agents with different behaviors, strategies, and information connectivity. A jump-diffusion process simulating events that may occur in the market is introduced. Agents information awareness varies along with agents propensity to respond to the information jump and jump size. A jump reshuffles market positions based on agents risk preferences determined by behavior and strategy. We examine the effect of information awareness on the volatility index of the simulated market in a scale-free market network. The analysis is performed by developing five experiments wherein the first one corresponds to systemic information ignorance state. Three experiments examine the role of hubs, normal agents, and hermits in the network when intermediate combinations of agent types have information awareness. The fifth experiment corresponds to the systemic information awareness with all agents being informed. The results show that the simulated market is driven to instability in a similar manner to patterns observed in a crisis where all agents become homogeneous in information awareness of events. Hubs contribute to increased connectivity and act as amplifiers of good, bad, or inaccurate information or sentiment.


2006 ◽  
Vol 2 (S235) ◽  
pp. 124-124
Author(s):  
J. M. Meyer ◽  
J. J. Dalcanton ◽  
T. R. Quinn ◽  
L. L. R. Williams ◽  
E. I. Barnes ◽  
...  

AbstractFor nearly a decade, N-body simulations have revealed a nearly universal dark matter density profile. This density profile appears to be robust to changes in the overall density of the universe and the underlying power spectrum. Despite its universality, however, the physical origin of this profile has not yet been well understood. Semi-analytic models have suggested that scale lengths in dark matter halos may be determined by the onset of the radial orbit instability. We have tested this theory using N-body simulations of collapsing dark matter halos. The resulting halo structures are prolate in shape, due to the mild aspect of the instability. We find that the radial orbit instability sets a scale length at which the velocity dispersion changes rapidly from isotropic to radially anisotropic. Preliminary analysis suggests that this scale length is proportional to the radius at which the density profile changes shape, as is the case in the semi-analytic models; however, the coefficient of proportionality is different by a factor of ~2. We conclude that the radial orbit instability may be a key physical mechanism responsible for the nearly universal profiles of simulated dark matter halos.


2014 ◽  
Vol 47 (34) ◽  
pp. 345002 ◽  
Author(s):  
P Lansky ◽  
F Polito ◽  
L Sacerdote

Author(s):  
M. Vynnycky ◽  
N. Ipek

Asymptotic methods are used to explore the role of one of the homogeneous chemical reactions, water protolysis, in a recent numerical model for the electrochemical pickling of steel. The analysis helps to interpret the somewhat surprising results of the original numerical model: that the local current density profile at the pickled strip does not depend on whether the water protolysis reaction is included in the model or not. The analysis also gives a useful systematic approach for determining qualitative estimates for the width of reaction boundary layers at cell electrodes, which can be of help when designing a computational mesh for the numerical solution of electrochemical models that have such layers.


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