5,968 research outputs found
Multi-scale 3-D Surface Description: Open and Closed Surfaces
A novel technique for multi-scale smoothing of a free-form 3-D surface is presented. Complete triangulated models of 3-D objects are constructed automatically and using a local parametrization technique, are then smoothed using a 2-D Gaussian filter. Our method for local parametrization makes use of semigeodesic coordinates as a natural and efficient way of sampling the local surface shape. The smoothing eliminates the surface noise together with high curvature regions such as sharp edges, therefore, sharp corners become rounded as the object is smoothed iteratively. Our technique for free-form 3-D multi-scale surface smoothing is independent of the underlying triangulation. It is also argued that the proposed technique is preferrable to volumetric smoothing or level set methods since it is applicable to incomplete surface data which occurs during occlusion. Our technique was applied to closed as well as open 3-D surfaces and the results are presented here
Multi-Scale Free-Form Surface Description and Curvature Estimation
A novel technique for multi-scale smoothing of a free-form 3-D surface is presented. Complete triangulated models of 3-D objects are constructed at our center [4] and using a local parametrization technique, are then smoothed using a 2-D Gaussian filter. Our method for local parametrization makes use of semigeodesic coordinates as a natural and efficient way of sampling the local surface shape. The smoothing eliminates the surface noise together with high curvature regions such as sharp edges, therefore, sharp corners become rounded as the object is smoothed iteratively. Our technique for free-form 3-D multi-scale surface smoothing is independent of the underlying triangulation. It is also argued that the proposed technique is preferrable to volumetric smoothing or level set methods since it is applicable to incomplete surface data which occurs during occlusion. The technique was applied to simple and complex 3-D objects and the results are presented here
Quantum Communications with Compressed Decoherence Using Bright Squeezed Light
We propose a scheme for long-distance distribution of quantum entanglement in
which the entanglement between qubits at intermediate stations of the channel
is established by using bright light pulses in squeezed states coupled to the
qubits in cavities with a weak dispersive interaction. The fidelity of the
entanglement between qubits at the neighbor stations (10 km apart from each
other) obtained by postselection through the balanced homodyne detection of 7
dB squeezed pulses can reach F=0.99 without using entanglement purification, at
same time, the probability of successful generation of entanglement is 0.34.Comment: 4 pages, 2 figure
Self-Similar Blowup Solutions to the 2-Component Camassa-Holm Equations
In this article, we study the self-similar solutions of the 2-component
Camassa-Holm equations% \begin{equation} \left\{ \begin{array} [c]{c}%
\rho_{t}+u\rho_{x}+\rho u_{x}=0
m_{t}+2u_{x}m+um_{x}+\sigma\rho\rho_{x}=0 \end{array} \right. \end{equation}
with \begin{equation} m=u-\alpha^{2}u_{xx}. \end{equation} By the separation
method, we can obtain a class of blowup or global solutions for or
. In particular, for the integrable system with , we have the
global solutions:% \begin{equation} \left\{ \begin{array} [c]{c}%
\rho(t,x)=\left\{ \begin{array} [c]{c}% \frac{f\left( \eta\right)
}{a(3t)^{1/3}},\text{ for }\eta^{2}<\frac {\alpha^{2}}{\xi}
0,\text{ for }\eta^{2}\geq\frac{\alpha^{2}}{\xi}% \end{array} \right.
,u(t,x)=\frac{\overset{\cdot}{a}(3t)}{a(3t)}x
\overset{\cdot\cdot}{a}(s)-\frac{\xi}{3a(s)^{1/3}}=0,\text{ }a(0)=a_{0}%
>0,\text{ }\overset{\cdot}{a}(0)=a_{1}
f(\eta)=\xi\sqrt{-\frac{1}{\xi}\eta^{2}+\left( \frac{\alpha}{\xi}\right)
^{2}}% \end{array} \right. \end{equation}
where with and are
arbitrary constants.\newline Our analytical solutions could provide concrete
examples for testing the validation and stabilities of numerical methods for
the systems.Comment: 5 more figures can be found in the corresponding journal paper (J.
Math. Phys. 51, 093524 (2010) ). Key Words: 2-Component Camassa-Holm
Equations, Shallow Water System, Analytical Solutions, Blowup, Global,
Self-Similar, Separation Method, Construction of Solutions, Moving Boundar
Can ultrastrong coupling change ground state chemical reactions?
Recent advancements on the fabrication of organic micro- and nanostructures
have permitted the strong collective light-matter coupling regime to be reached
with molecular materials. Pioneering works in this direction have shown the
effects of this regime in the excited state reactivity of molecular systems and
at the same time has opened up the question of whether it is possible to
introduce any modifications in the electronic ground energy landscape which
could affect chemical thermodynamics and/or kinetics. In this work, we use a
model system of many molecules coupled to a surface-plasmon field to gain
insight on the key parameters which govern the modifications of the
ground-state Potential Energy Surface (PES). Our findings confirm that the
energetic changes per molecule are determined by single-molecule-light
couplings which are essentially local, in contrast with those of the
electronically excited states, for which energetic corrections are of a
collective nature. Still, we reveal some intriguing quantum-coherent effects
associated with pathways of concerted reactions, where two or more molecules
undergo reactions simultaneously, and which can be of relevance in low-barrier
reactions. Finally, we also explore modifications to nonadiabatic dynamics and
conclude that, for this particular model, the presence of a large number of
dark states yields negligible changes. Our study reveals new possibilities as
well as limitations for the emerging field of polariton chemistry
Bosonic Memory Channels
We discuss a Bosonic channel model with memory effects. It relies on a
multi-mode squeezed (entangled) environment's state. The case of lossy Bosonic
channels is analyzed in detail. We show that in the absence of input energy
constraints the memory channels are equivalent to their memoryless
counterparts. In the case of input energy constraint we provide lower and upper
bounds for the memory channel capacity.Comment: 6 pages, 2 figure
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