5,294 research outputs found
Electron transfer theory revisit: Quantum solvation effect
The effect of solvation on the electron transfer (ET) rate processes is
investigated on the basis of the exact theory constructed in J. Phys. Chem. B
Vol. 110, (2006); quant-ph/0604071. The nature of solvation is studied in a
close relation with the mechanism of ET processes. The resulting Kramers'
turnover and Marcus' inversion characteristics are analyzed accordingly. The
classical picture of solvation is found to be invalid when the solvent
longitudinal relaxation time is short compared with the inverse temperature.Comment: 5 pages, 3 figures. J. Theo. & Comput. Chem., accepte
Delayed Onset and Fast Rise of Prompt Optical-UV Emission from Gamma-Ray Bursts in Molecular Clouds
Observations imply that long \gamma-ray bursts (GRBs) are originated from
explosions of massive stars, therefore they may occur in the molecular clouds
where their progenitors were born. We show here that the prompt optical-UV
emission from GRBs may be delayed due to the dust extinction, which can well
explain the observed optical delayed onset and fast rise in GRB 080319B. The
density and the size of the molecular cloud around GRB 080319B are roughly
constrained to be \sim10^3cm^{-3} and \sim 8pc, respectively. We also
investigate the other GRBs with prompt optical-UV data, and find similar values
of the densities and sizes of the local molecular clouds. The future
observations of prompt optical-UV emission from GRBs in subsecond timescale,
e.g., by UFFO-Pathfinder and SVOM-GWAC, will provide more evidence and probes
of the local GRB environments.Comment: 15 pages, 5 figures, RAA 13 (2013) 57-70, typo correctio
Linear Global Translation Estimation with Feature Tracks
This paper derives a novel linear position constraint for cameras seeing a
common scene point, which leads to a direct linear method for global camera
translation estimation. Unlike previous solutions, this method deals with
collinear camera motion and weak image association at the same time. The final
linear formulation does not involve the coordinates of scene points, which
makes it efficient even for large scale data. We solve the linear equation
based on norm, which makes our system more robust to outliers in
essential matrices and feature correspondences. We experiment this method on
both sequentially captured images and unordered Internet images. The
experiments demonstrate its strength in robustness, accuracy, and efficiency.Comment: Changes: 1. Adopt BMVC2015 style; 2. Combine sections 3 and 5; 3.
Move "Evaluation on synthetic data" out to supplementary file; 4. Divide
subsection "Evaluation on general data" to subsections "Experiment on
sequential data" and "Experiment on unordered Internet data"; 5. Change Fig.
1 and Fig.8; 6. Move Fig. 6 and Fig. 7 to supplementary file; 7 Change some
symbols; 8. Correct some typo
Power vs. Spectrum 2-D Sensing in Energy Harvesting Cognitive Radio Networks
Energy harvester based cognitive radio is a promising solution to address the
shortage of both spectrum and energy. Since the spectrum access and power
consumption patterns are interdependent, and the power value harvested from
certain environmental sources are spatially correlated, the new power dimension
could provide additional information to enhance the spectrum sensing accuracy.
In this paper, the Markovian behavior of the primary users is considered, based
on which we adopt a hidden input Markov model to specify the primary vs.
secondary dynamics in the system. Accordingly, we propose a 2-D spectrum and
power (harvested) sensing scheme to improve the primary user detection
performance, which is also capable of estimating the primary transmit power
level. Theoretical and simulated results demonstrate the effectiveness of the
proposed scheme, in term of the performance gain achieved by considering the
new power dimension. To the best of our knowledge, this is the first work to
jointly consider the spectrum and power dimensions for the cognitive primary
user detection problem
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