Friday, December 04, 2009

CS: Exact Optimization for the l1-Compressive Sensing problem using a Modified Dantzig-Wolfe method and two presentations

I just added a sentence by Howard Aiken at the end of the These Technologies Do Not Exist page, it's: “Don’t worry about people stealing your ideas. If it’s original, you’ll have to ram it down their throats.”.... and then when you have done that, you may have to fight the FCC (UWB radar for wall see through) and/or the lawyers (isn't the title of this patent summarizing what reconstruction solvers do in compressive sensing ?). Anyway, to conclude these eventful two weeks, I just found one paper and two presentations:

Exact Optimization for the l1-Compressive Sensing problem using a Modified Dantzig-Wolfe method by Alexandre Borghi, Jerome Darbon, Sylvain Peyronnet. The abstract reads:
This paper considers the l1-Compressive Sensing problem and presents an efficient algorithm that computes an exact solution. The idea consists in reformulating the problem such that it yields a modified Dantzig-Wolfe decomposition that allows to efficiently apply all standard simplex pivoting rules. Experimental results show the superiority of our approach compared to standard linear programming methods.
I am looking forward to an implementation of this algorithm. And the presentations:
Today is also the PhD Final Oral Defense of Nishant Mohan at Boston University. From the University Calendar:


BME PhD Final Oral Defense of Nishant Mohan

"Photon-Counting Optical Coherence-Domain Imaging" ABSTRACT: Coherence-domain imaging (CDI) systems can be operated in a single-photon counting mode, offering low detector noise; this in turn leads to increased sensitivity for weak light sources and weakly reflecting samples. In this thesis, I demonstrate that excellent axial resolution can be obtained in a photon-counting coherence-domain imaging (PC-CDI) system that uses light generated via spontaneous parametric down-conversion (SPDC) in a chirped periodically poled stoichiometric lithium tantalate (chirped-PPSLT) structure, in conjunction with a niobium nitride superconducting single-photon detector (SSPD). The bandwidth of the light generated via SPDC, as well as the bandwidth over which the SSPD is sensitive, can extend over a wavelength region that stretches from 700 to 1500 nm. This ultra-broad wavelength band offers a near-ideal combination of deep penetration and ultra-high axial resolution for the imaging of biological tissue. The generation of SPDC light of adjustable bandwidth in the vicinity of 1064 nm, via the use of chirped-PPSLT structures, is novel. To demonstrate the usefulness of PC-CDI, I have constructed images for a hierarchy of samples of increasing complexity: a mirror, a nitrocellulose membrane, and a biological sample comprising onion-skin cells. The potential usefulness of this technique in a standard configuration is limited, however, by the presence of 1/f-type noise in the source of illumination. I have therefore investigated this noise for various sources of light that are useful in optical imaging. Finally, I consider another CDI configuration, spectral-domain imaging, and show that the notion of compressed sensing can be useful for simplifying the experimental configuration.

10:00am on Friday, December 4th 2009

Photonics Center, 8 St. Mary's Street (PHO 404)

Seminars and Lectures, Biomedical Engineering

Credit photo: NAS, STS-129 ascent as viewed by a camera on-board one of the solid rocket boosters.

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