scholarly journals Dedalus: A flexible framework for numerical simulations with spectral methods

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Keaton J. Burns ◽  
Geoffrey M. Vasil ◽  
Jeffrey S. Oishi ◽  
Daniel Lecoanet ◽  
Benjamin P. Brown
Keyword(s):  
Numerical Simulations ◽  
Spectral Methods ◽  
Flexible Framework

Meta-Accuracy and Perceived Reciprocity From the Perception-Meta-Perception Social Relations Model

2019 ◽  
Vol 50 (1) ◽  
pp. 24-37
Author(s):  
Ben Porter ◽  
Camilla S. Øverup ◽  
Julie A. Brunson ◽  
Paras D. Mehta
Keyword(s):  
Structural Equation Modeling ◽  
Social Relations ◽  
Latent Variables ◽  
Structural Equation ◽  
Multilevel Structural Equation Modeling ◽  
Equation Modeling ◽  
Complete Understanding ◽  
Social Relations Model ◽  
Flexible Framework ◽  
Multilevel Structural Equation

Abstract. Meta-accuracy and perceptions of reciprocity can be measured by covariances between latent variables in two social relations models examining perception and meta-perception. We propose a single unified model called the Perception-Meta-Perception Social Relations Model (PM-SRM). This model simultaneously estimates all possible parameters to provide a more complete understanding of the relationships between perception and meta-perception. We describe the components of the PM-SRM and present two pedagogical examples with code, openly available on https://osf.io/4ag5m . Using a new package in R (xxM), we estimated the model using multilevel structural equation modeling which provides an approachable and flexible framework for evaluating the PM-SRM. Further, we discuss possible expansions to the PM-SRM which can explore novel and exciting hypotheses.

Analyzing Stochastic Dependence of Cognitive Processes in Multidimensional Source Recognition

2014 ◽  
Vol 61 (5) ◽  
pp. 402-415 ◽  
Author(s):  
Thorsten Meiser
Keyword(s):  
Cognitive Processes ◽  
Model Complexity ◽  
Multinomial Model ◽  
Stochastic Dependence ◽  
New Model ◽  
Multinomial Processing Tree ◽  
Cognitive States ◽  
The Family ◽  
Tree Models ◽  
Flexible Framework

Stochastic dependence among cognitive processes can be modeled in different ways, and the family of multinomial processing tree models provides a flexible framework for analyzing stochastic dependence among discrete cognitive states. This article presents a multinomial model of multidimensional source recognition that specifies stochastic dependence by a parameter for the joint retrieval of multiple source attributes together with parameters for stochastically independent retrieval. The new model is equivalent to a previous multinomial model of multidimensional source memory for a subset of the parameter space. An empirical application illustrates the advantages of the new multinomial model of joint source recognition. The new model allows for a direct comparison of joint source retrieval across conditions, it avoids statistical problems due to inflated confidence intervals and does not imply a conceptual imbalance between source dimensions. Model selection criteria that take model complexity into account corroborate the new model of joint source recognition.

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

Finite volume and spectral methods applied to Pb-30%TI alloy solidification

2001 ◽  
Vol 11 (PR6) ◽  
pp. Pr6-151-Pr6-159 ◽  
Author(s):  
R. Guérin ◽  
M. El Ganaoui ◽  
P. Haldenwang ◽  
P. Bontoux
Keyword(s):  
Finite Volume ◽  
Spectral Methods ◽  
Ti Alloy ◽  
Alloy Solidification

The Belt and Road Initiative and Sino-Russian economic cooperation: Is there one more chance for us?

2019 ◽  
pp. 47-71
Author(s):  
Petr M. Mozias
Keyword(s):  
Regional Integration ◽  
Raw Materials ◽  
Belt And Road Initiative ◽  
Stage Of Development ◽  
Belt And Road ◽  
Flexible Framework ◽  
The One ◽  
International Transactions ◽  
The Belt And Road ◽  
Current Stage

China’s Belt and Road Initiative could be treated ambiguously. On the one hand, it is intended to transform the newly acquired economic potential of that country into its higher status in the world. China invites a lot of nations to build up gigantic transit corridors by joint efforts, and doing so it applies productively its capital and technologies. International transactions in RMB are also being expanded. But, on the other hand, the Belt and Road Initiative is also a necessity for China to cope with some evident problems of its current stage of development, such as industrial overcapacity, overdependence on imports of raw materials from a narrow circle of countries, and a subordinate status in global value chains. For Russia participation in the Belt and Road Initiative may be fruitful, since the very character of that project provides us with a space to manoeuvre. By now, Russian exports to China consist primarily of fuels and other commodities. More active industrial policy is needed to correct this situation . A flexible framework of the Belt and Road Initiative is more suitable for this objective to be achieved, rather than traditional forms of regional integration, such as a free trade zone.

CHARACTERIZATION OF SPLASH-PLATE ATOMIZERS USING NUMERICAL SIMULATIONS

2007 ◽  
Vol 17 (4) ◽  
pp. 347-380 ◽  
Author(s):  
Mohammad P. Fard ◽  
Denise Levesque ◽  
Stuart Morrison ◽  
Nasser Ashgriz ◽  
J. Mostaghimi
Keyword(s):  
Numerical Simulations
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