1,092 research outputs found
The inner mass power spectrum of galaxies using strong gravitational lensing: beyond linear approximation
In the last decade the detection of individual massive dark matter sub-halos
has been possible using potential correction formalism in strong gravitational
lens imaging. Here we propose a statistical formalism to relate strong
gravitational lens surface brightness anomalies to the lens potential
fluctuations arising from dark matter distribution in the lens galaxy. We
consider these fluctuations as a Gaussian random field in addition to the
unperturbed smooth lens model. This is very similar to weak lensing formalism
and we show that in this way we can measure the power spectrum of these
perturbations to the potential. We test the method by applying it to simulated
mock lenses of different geometries and by performing an MCMC analysis of the
theoretical power spectra. This method can measure density fluctuations in
early type galaxies on scales of 1-10 kpc at typical rms-levels of a percent,
using a single lens system observed with the Hubble Space Telescope with
typical signal-to-noise ratios obtained in a single orbit
Dynamic Iterative Pursuit
For compressive sensing of dynamic sparse signals, we develop an iterative
pursuit algorithm. A dynamic sparse signal process is characterized by varying
sparsity patterns over time/space. For such signals, the developed algorithm is
able to incorporate sequential predictions, thereby providing better
compressive sensing recovery performance, but not at the cost of high
complexity. Through experimental evaluations, we observe that the new algorithm
exhibits a graceful degradation at deteriorating signal conditions while
capable of yielding substantial performance gains as conditions improve.Comment: 6 pages, 7 figures. Accepted for publication in IEEE Transactions on
Signal Processin
Distributed Quantization for Compressed Sensing
We study distributed coding of compressed sensing (CS) measurements using
vector quantizer (VQ). We develop a distributed framework for realizing
optimized quantizer that enables encoding CS measurements of correlated sparse
sources followed by joint decoding at a fusion center. The optimality of VQ
encoder-decoder pairs is addressed by minimizing the sum of mean-square errors
between the sparse sources and their reconstruction vectors at the fusion
center. We derive a lower-bound on the end-to-end performance of the studied
distributed system, and propose a practical encoder-decoder design through an
iterative algorithm.Comment: 5 Pages, Accepted for presentation in ICASSP 201
Channel-Optimized Vector Quantizer Design for Compressed Sensing Measurements
We consider vector-quantized (VQ) transmission of compressed sensing (CS)
measurements over noisy channels. Adopting mean-square error (MSE) criterion to
measure the distortion between a sparse vector and its reconstruction, we
derive channel-optimized quantization principles for encoding CS measurement
vector and reconstructing sparse source vector. The resulting necessary optimal
conditions are used to develop an algorithm for training channel-optimized
vector quantization (COVQ) of CS measurements by taking the end-to-end
distortion measure into account.Comment: Published in ICASSP 201
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