Nonequilibrium Thermodynamics and Entropy Production in Simulation of Electrical Tree Growth

In the present work we applied the nonequilibrium thermodynamic theory in the analysis of the dielectric breakdown (DB) process. As the tree channel front moves, the intense field near the front moves electrons and ions irreversibly in the region beyond the tree channel tips where electromechanical, thermal and chemical effects cause irreversible damage and, from the nonequilibrium thermodynamic viewpoint, entropy production. From the nonequilibrium thermodynamics analysis, the entropy production is due to the product of fluxes Ji and conjugated forces Xi: σ = ∑iJiXi ≥ 0. We consider that the coupling between fluxes can describe the dielectric breakdown in solids as a phenomenon of transport of heat, mass and electric charge.

Automatic LOD selection using viewpoint entropy

Discrete Level of Detail (LOD) strategy is an effective solution for balancing the inherent contradiction between quality and speed in computer graphics. However, application of this strategy requires both the appropriate selection approach and the visually comfortable transition procedure to reduce the popping effects introduced by switching between different levels. In this paper, a novel automatic LOD selection method based on viewpoint entropy was proposed. Firstly, the traditional calculation method of viewpoint entropy contained in a scene was improved for the preprocessing of LOD models. Then, the runtime rendering scheme combined with our selection method was designed for balance of frame rate during real-time rendering, and a novel smoothing LOD transition strategy based on Alternate Frame Rendered (ALR) was put forward for elimination of popping effects. Finally, an example of complex scene combined with our proposal was researched to verify its real-time performance and ability in holding continuity of rendered images. Experimental studies show the effectiveness for stabilizing frame rate and improvements in reducing loss of continuity.