The precession of eccentric discs in close binaries

We consider the precession rates of eccentric discs in close binaries, and compare theoretical predictions with the results of numerical disc simulations and with observed superhump periods. A simple dynamical model for precession is found to be inadequate. For mass ratios less than approximately 1/4 a linear dynamical model does provide an upper limit for disc precession rates. Theory suggests that pressure forces have a significant retrograde impact upon the precession rate (Lubow 1992). We find that the disc precession rates for three systems with accurately known mass ratios are significantly slower than predicted by the dynamical theory, and we attribute the difference to pressure forces. By assuming that pressure forces of similar magnitude occur in all superhumping systems, we obtain an improved fit to superhump observations.Comment: 6 pages to appear in MNRAS (accepted

Diffusive Domain Coarsening : Early Time Dynamics and Finite-Size Effects

We study diffusive dynamics of phase separation in a binary mixture, following critical quench, both in spatial dimensions $d=2$ and $d=3$. Particular focus in this work is to obtain information about effects of system size and correction to the growth law via appropriate application of finite-size scaling method to the results obtained from Kawasaki exchange Monte Carlo simulation of Ising model. Observations of only weak size effects and very small correction to scaling in the growth law are significant. The methods used in this work and information thus gathered will be of paramount importance in the study of kinetics of phase separation in fluids and other problems of growing length scale. We also provide detailed discussion on standard methods of understanding simulation results which may lead to inappropriate conclusions.Comment: 11 pages, 12 figure

Fast Domain Growth through Density-Dependent Diffusion in a Driven Lattice Gas

We study electromigration in a driven diffusive lattice gas (DDLG) whose continuous Monte Carlo dynamics generate higher particle mobility in areas with lower particle density. At low vacancy concentrations and low temperatures, vacancy domains tend to be faceted: the external driving force causes large domains to move much more quickly than small ones, producing exponential domain growth. At higher vacancy concentrations and temperatures, even small domains have rough boundaries: velocity differences between domains are smaller, and modest simulation times produce an average domain length scale which roughly follows $L \sim t^{\zeta}$, where $\zeta$ varies from near .55 at 50% filling to near .75 at 70% filling. This growth is faster than the $t^{1/3}$ behavior of a standard conserved order parameter Ising model. Some runs may be approaching a scaling regime. At low fields and early times, fast growth is delayed until the characteristic domain size reaches a crossover length which follows $L_{cross} \propto E^{-\beta}$. Rough numerical estimates give $\beta= >.37$ and simple theoretical arguments give $\beta= 1/3$. Our conclusion that small driving forces can significantly enhance coarsening may be relevant to the YB$_2$Cu$_3$O$_{7- \delta}$ electromigration experiments of Moeckly {\it et al.}(Appl. Phys. Let., {\bf 64}, 1427 (1994)).Comment: 18 pages, RevTex3.

Diversity and Social Network Structure in Collective Decision Making: Evolutionary Perspectives with Agent-Based Simulations

Collective, especially group-based, managerial decision making is crucial in organizations. Using an evolutionary theoretic approach to collective decision making, agent-based simulations were conducted to investigate how human collective decision making would be affected by the agents' diversity in problem understanding and/or behavior in discussion, as well as by their social network structure. Simulation results indicated that groups with consistent problem understanding tended to produce higher utility values of ideas and displayed better decision convergence, but only if there was no group-level bias in collective problem understanding. Simulation results also indicated the importance of balance between selection-oriented (i.e., exploitative) and variation-oriented (i.e., explorative) behaviors in discussion to achieve quality final decisions. Expanding the group size and introducing non-trivial social network structure generally improved the quality of ideas at the cost of decision convergence. Simulations with different social network topologies revealed collective decision making on small-world networks with high local clustering tended to achieve highest decision quality more often than on random or scale-free networks. Implications of this evolutionary theory and simulation approach for future managerial research on collective, group, and multi-level decision making are discussed.Comment: 27 pages, 5 figures, 2 tables; accepted for publication in Complexit

Populating 3D Cities: a True Challenge

In this paper, we describe how we can model crowds in real-time using dynamic meshes, static meshes andimpostors. Techniques to introduce variety in crowds including colors, shapes, textures, individualanimation, individualized path-planning, simple and complex accessories are explained. We also present ahybrid architecture to handle the path planning of thousands of pedestrians in real time, while ensuringdynamic collision avoidance. Several behavioral aspects are presented as gaze control, group behaviour, aswell as the specific technique of crowd patches

Populating 3D Cities: A True Challenge

In this paper, we describe how we can model crowds in real-time using dynamic meshes, static meshes andimpostors. Techniques to introduce variety in crowds including colors, shapes, textures, individualanimation, individualized path-planning, simple and complex accessories are explained. We also present ahybrid architecture to handle the path planning of thousands of pedestrians in real time, while ensuringdynamic collision avoidance. Several behavioral aspects are presented as gaze control, group behaviour, aswell as the specific technique of crowd patches

Data Analysis of Social Simulations Outputs - Focus on variables dispersion

International audienceIn the domain of social simulation, there are very few papers reporting on the statistical analysis of simulation results, while it is very common in empirical social sciences. The paper advocates the expansion of the statistical analysis of social simulation outputs, as a very efficient way to improve the interpretation of simulation results and so the understanding of the system that is the model's target. This is illustrated by the study of a simulation model designed to analyze a real situation related to the management of a river in South West of France. Several standard statistics methods are used to shed light on the possible outcomes of the discussion between the actors

Agent-Based Modeling for Efficiency Policy of Households\u27 Electricity Consumption in Bandung City

There are many argumentations that the government subsidy in electricity, for holding down the electricity fares, has encouraged extravagant use of electricity. Therefore, the Government Budget (APBN) Burden for this subsidy becomes higher than it necessary. Some experts have argued that this money can actually be used for other necessary and urgent spending such as infrastructure development. The purpose of this research is to build an agent-based model and simulation to explore the dinamic of electricity consumption in Indonesia, especially in Bandung City. Several interviews were conducted about households\u27 behaviors in consuming electricity to build the model. Then, the parameter was set based on the data collected with questionaire and secondary data source. The model was tested for its validity and sensitivity to the change in the controlled parameter. The simulation is expected to provide the government with a combination of electricity fare to various households electricity market segments to ensure an economic use of electricity. Some scenarios were run and the emergent property, the whole system electricity consumption,were observed to find out the best policy to encourage efficient use of electricity in the system

Agent-Based Modeling for Efficiency Policy of Households' Electricity Consumption in Bandung City

There are many argumentations that the government subsidy in electricity, for holding down the electricity fares, has encouraged extravagant use of electricity. Therefore, the Government Budget (APBN) Burden for this subsidy becomes higher than it necessary. Some experts have argued that this money can actually be used for other necessary and urgent spending such as infrastructure development. The purpose of this research is to build an agent-based model and simulation to explore the dinamic of electricity consumption in Indonesia, especially in Bandung City. Several interviews were conducted about households' behaviors in consuming electricity to build the model. Then, the parameter was set based on the data collected with questionaire and secondary data source. The model was tested for its validity and sensitivity to the change in the controlled parameter. The simulation is expected to provide the government with a combination of electricity fare to various households electricity market segments to ensure an economic use of electricity. Some scenarios were run and the emergent property, the whole system electricity consumption,were observed to find out the best policy to encourage efficient use of electricity in the system.Keywords: agent-based modeling, electricity consumption, electricity fare, households, simulation,electricity cost