71,861 research outputs found
On the weighted forward reduced Entropy of Ricci flow
In this paper, we first introduce the weighted forward reduced volume of
Ricci flow. The weighted forward reduced volume, which related to expanders of
Ricci flow, is well-defined on noncompact manifolds and monotone non-increasing
under Ricci flow. Moreover, we show that, just the same as the Perelman's
reduced volume, the weighted reduced volume entropy has the value
if and only if the Ricci flow is the trivial flow on
flat Euclidean space.Comment: 10 page
Analyses of celestial pole offsets with VLBI, LLR, and optical observations
This work aims to explore the possibilities of determining the long-period
part of the precession-nutation of the Earth with techniques other than very
long baseline interferometry (VLBI). Lunar laser ranging (LLR) is chosen for
its relatively high accuracy and long period. Results of previous studies could
be updated using the latest data with generally higher quality, which would
also add ten years to the total time span. Historical optical data are also
analyzed for their rather long time-coverage to determine whether it is
possible to improve the current Earth precession-nutation model
- …