6,967 research outputs found
On the Smarandache sequences
In this paper, one uses the elementary method to study the convergence of the Smarandache alternate consecutive, reverse Fibonacci sequence and Smarandache multiple sequence
Reversible Transient Nucleation in Ionic Solutions as the Precursor of Ion Crystallization
Molecular dynamics simulations for aqueous sodium chloride solutions were
carried out at various concentrations. Supplementary to the Debye-H\"uckel
theory, reversible transient nucleation of ions was observed even in dilute
solutions. The average size of formed ion clusters and the lifetime of ion
pairs increase with concentration until the saturation point, when ion clusters
become stable and individual ions adjust their positions to form ordered
lattice structures, leading to irreversible ion crystallization, which is
beyond the description of the classical nucleation theory.Comment: 4 pages, 5 figures, and 46 reference
Analysis of Approximate Message Passing with a Class of Non-Separable Denoisers
Approximate message passing (AMP) is a class of efficient algorithms for
solving high-dimensional linear regression tasks where one wishes to recover an
unknown signal \beta_0 from noisy, linear measurements y = A \beta_0 + w. When
applying a separable denoiser at each iteration, the performance of AMP (for
example, the mean squared error of its estimates) can be accurately tracked by
a simple, scalar iteration referred to as state evolution. Although separable
denoisers are sufficient if the unknown signal has independent and identically
distributed entries, in many real-world applications, like image or audio
signal reconstruction, the unknown signal contains dependencies between
entries. In these cases, a coordinate-wise independence structure is not a good
approximation to the true prior of the unknown signal. In this paper we assume
the unknown signal has dependent entries, and using a class of non-separable
sliding-window denoisers, we prove that a new form of state evolution still
accurately predicts AMP performance. This is an early step in understanding the
role of non-separable denoisers within AMP, and will lead to a characterization
of more general denoisers in problems including compressive image
reconstruction.Comment: 37 pages, 1 figure. A shorter version of this paper to appear in the
proceedings of ISIT 201
Compressive Imaging via Approximate Message Passing with Image Denoising
We consider compressive imaging problems, where images are reconstructed from
a reduced number of linear measurements. Our objective is to improve over
existing compressive imaging algorithms in terms of both reconstruction error
and runtime. To pursue our objective, we propose compressive imaging algorithms
that employ the approximate message passing (AMP) framework. AMP is an
iterative signal reconstruction algorithm that performs scalar denoising at
each iteration; in order for AMP to reconstruct the original input signal well,
a good denoiser must be used. We apply two wavelet based image denoisers within
AMP. The first denoiser is the "amplitude-scaleinvariant Bayes estimator"
(ABE), and the second is an adaptive Wiener filter; we call our AMP based
algorithms for compressive imaging AMP-ABE and AMP-Wiener. Numerical results
show that both AMP-ABE and AMP-Wiener significantly improve over the state of
the art in terms of runtime. In terms of reconstruction quality, AMP-Wiener
offers lower mean square error (MSE) than existing compressive imaging
algorithms. In contrast, AMP-ABE has higher MSE, because ABE does not denoise
as well as the adaptive Wiener filter.Comment: 15 pages; 2 tables; 7 figures; to appear in IEEE Trans. Signal
Proces
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