8,686 research outputs found
Simple and Robust Boolean Operations for Triangulated Surfaces
Boolean operations of geometric models is an essential issue in computational
geometry. In this paper, we develop a simple and robust approach to perform
Boolean operations on closed and open triangulated surfaces. Our method mainly
has two stages: (1) We firstly find out candidate intersected-triangles pairs
based on Octree and then compute the inter-section lines for all pairs of
triangles with parallel algorithm; (2) We form closed or open
intersection-loops, sub-surfaces and sub-blocks quite robustly only according
to the cleared and updated topology of meshes while without coordinate
computations for geometric enti-ties. A novel technique instead of
inside/outside classification is also proposed to distinguish the resulting
union, subtraction and intersection. Several examples have been given to
illus-trate the effectiveness of our approach.Comment: Novel method for determining Union, Subtraction and Intersectio
Charge Conjugation Violation in Supernovae and The Neutron Shortage for R-Process Nucelosynthesis
Core collapse supernovae are dominated by energy transport from neutrinos.
Therefore, some supernova properties could depend on symetries and features of
the standard model weak interactions. The cross section for neutrino capture is
larger than that for antineutrino capture by one term of order the neutrino
energy over the nucleon mass. This reduces the ratio of neutrons to protons in
the -driven wind above a protoneutron star by approximately 20 % and may
significantly hinder r-process nucleosynthesis.Comment: Proceedings of Intersections Conference, Qube
Russian Cities in Transition: The Impact of Market Forces in the 1990s
This paper analyses Russian city growth during the command and transition eras. Our main focus is on understanding the extent to which market forces are replacing command forces, and the resulting changes in Russian city growth patterns. We examine net migration rates for a sample of 171 medium and large cities for the period 1960 through 2002. We conclude that while the declining net migration rate was reversed during the first half of the 1990s, restrictions continued to matter during the early years of transition in the sense that net migration rates were lower in the restricted than in the unrestricted cities. This pattern seemingly came to an end in the late 1990s.http://deepblue.lib.umich.edu/bitstream/2027.42/40083/3/wp697.pd
Discrete Surface Modeling Based on Google Earth: A Case Study
Google Earth (GE) has become a powerful tool for geological, geophysical and
geographical modeling; yet GE can be accepted to acquire elevation data of
terrain. In this paper, we present a real study case of building the discrete
surface model (DSM) at Haut-Barr Castle in France based on the elevation data
of terrain points extracted from GE using the COM API. We first locate the
position of Haut-Barr Castle and determine the region of the study area, then
extract elevation data of terrain at Haut-Barr, and thirdly create a planar
triangular mesh that covers the study area and finally generate the desired DSM
by calculating the elevation of vertices in the planar mesh via interpolating
with Universal Kriging (UK) and Inverse Distance Weighting (IDW). The generated
DSM can reflect the features of the ground surface at Haut-Barr well, and can
be used for constructingthe Sealed Engineering Geological Model (SEGM) in
further step.Comment: Proceedings of IEEE Conference, ICCSNT 2012, in Pres
The Modified Direct Method: an Approach for Smoothing Planar and Surface Meshes
The Modified Direct Method (MDM) is an iterative mesh smoothing method for
smoothing planar and surface meshes, which is developed from the non-iterative
smoothing method originated by Balendran [1]. When smooth planar meshes, the
performance of the MDM is effectively identical to that of Laplacian smoothing,
for triangular and quadrilateral meshes; however, the MDM outperforms Laplacian
smoothing for tri-quad meshes. When smooth surface meshes, for trian-gular,
quadrilateral and quad-dominant mixed meshes, the mean quality(MQ) of all mesh
elements always increases and the mean square error (MSE) decreases during
smoothing; For tri-dominant mixed mesh, the quality of triangles always
descends while that of quads ascends. Test examples show that the MDM is
convergent for both planar and surface triangular, quadrilateral and tri-quad
meshes.Comment: 18 page
- …