6,961 research outputs found
GPU-based Streaming for Parallel Level of Detail on Massive Model Rendering
Rendering massive 3D models in real-time has long been recognized as a very challenging problem because of the limited computational power and memory space available in a workstation. Most existing rendering techniques, especially level of detail (LOD) processing, have suffered from their sequential execution natures, and does not scale well with the size of the models. We present a GPU-based progressive mesh simplification approach which enables the interactive rendering of large 3D models with hundreds of millions of triangles. Our work contributes to the massive rendering research in two ways. First, we develop a novel data structure to represent the progressive LOD mesh, and design a parallel mesh simplification algorithm towards GPU architecture. Second, we propose a GPU-based streaming approach which adopt a frame-to-frame coherence scheme in order to minimize the high communication cost between CPU and GPU. Our results show that the parallel mesh simplification algorithm and GPU-based streaming approach significantly improve the overall rendering performance
Block Spin Ground State and 3-Dimensionality of (K,Tl)FeSe
The magnetic properties and electronic structure of (K,Tl)y Fe1.6 Se2 is
studied using first-principles calculations. The ground state is checkerboard
antiferromagnetically coupled blocks of the minimal Fe4 squares, with a large
block spin moment ~11.2{\mu}B . The magnetic interactions could be modelled
with a simple spin model involving both the inter- and intra-block, as well as
the n.n. and n.n.n. couplings. The calculations also suggest a metallic ground
state except for y = 0.8 where a band gap ~400 - 550 meV opens, showing an
antiferromagnetic insulator ground state for (K,Tl)0.8 Fe1.6 Se2 . The
electronic structure of the metallic (K,Tl)y Fe1.6 Se2 is highly 3-dimensional
with unique Fermi surface structure and topology. These features indicate that
the Fe-vacancy ordering is crucial to the physical properties of (K,Tl)y Fe2-x
Se2 .Comment: Magnetic coupling constants double checked, journal ref. adde
Theory for superconductivity in alkali chromium arsenides A2Cr3As3 (A=K,Rb,Cs)
We propose an extended Hubbard model with three molecular orbitals on a
hexagonal lattice with symmetry to study recently discovered
superconductivity in ACrAs (A=K,Rb,Cs). Effective pairing
interactions from paramagnon fluctuations are derived within the random phase
approximation, and are found to be most attractive in spin triplet channels. At
small Hubbard and moderate Hund's coupling, the pairing arises from
3-dimensional (3D) band and has a spatial symmetry
, which gives line nodes in the gap function. At large
, a fully gapped -wave state, dominates at the quasi-1D
-band
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