Visualizing opportunities: interview with Chris Harrison

My formal training is as a computer scientist. I went to New York University, got my bachelors and masters degrees in computer science. So, I am sort of a traditional programmer on one end - and then, after working in the industry, I came back to work on my Ph.D. in a fairly new field called Human-Computer Interaction (HCI), which is often described as the intersection of computer science, design, and cognitive science or behavioral science

Ray convergence in a flux-like propagation formulation

The energy flux formulation of waveguide propagation is closely related to the incoherent mode sum, and its simplicity has led to development of efficient computational algorithms for reverberation and target echo strength, but it lacks the effects of convergence or modal interference. By starting with the coherent mode sum and rejecting the most rapid interference but retaining beats on a scale of a ray cycle distance it is shown that convergence can be included in a hybrid formulation requiring minimal extra computation. Three solutions are offered by evaluating the modal intensity cross terms using Taylor expansions. In the most efficient approach the double summation of the cross terms is reduced to a single numerical sum by solving the other summation analytically. The other two solutions are a local range average and a local depth average. Favorable comparisons are made between these three solutions and the wave model Orca with, and without, spatial averaging in an upward refracting duct. As a by-product, it is shown that the running range average is very close to the mode solution excluding its fringes, given a relation between averaging window size and effective number of modes which, in turn, is related to the waveguide invariant

Maximum Entropy Estimation of the Galactic Bulge Morphology via the VVV Red Clump

The abundance and narrow magnitude dispersion of Red Clump (RC) stars make them a popular candidate for mapping the morphology of the bulge region of the Milky Way. Using an estimate of the RC's intrinsic luminosity function, we extracted the three-dimensional density distribution of the RC from deep photometric catalogues of the VISTA Variables in the Via Lactea (VVV) survey. We used maximum entropy based deconvolution to extract the spatial distribution of the bulge from Ks-band star counts. We obtained our extrapolated non-parametric model of the bulge over the inner 40 by 40 degrees squared region of the Galactic centre. Our reconstruction also naturally matches onto a parametric fit to the bulge outside the VVV region and inpaints overcrowded and high extinction regions. We found a range of bulge properties consistent with other recent investigations based on the VVV data. In particular, we estimated the bulge mass to be in the range 13 to 17 billion solar masses, the X-component to be between 18% and 25% of the bulge mass, and the bulge angle with respect to the Sun-Galactic centre line to be between 18 and 32 degrees. Studies of the Fermi Large Area Telescope (LAT) gamma-ray Galactic centre excess suggests that the excess may be traced by Galactic bulge distributed sources. We applied our deconvolved density in a template fitting analysis of this Fermi-LAT GeV excess and found an improvement in the fit compared to previous parametric based templates.Comment: 25 pages, 27 figures, minor typo correcte

Audio Universe: Tour of the Solar System

We have created a show about the Solar System, freely available for both planetariums and home viewing, where objects in space are represented with sound as well as with visuals. For example, the audience listens to the stars appear above the European Southern Observatory's Very Large Telescope and they hear the planets orbit around their heads. The aim of this show is that it can be enjoyed and understood, irrespective of level of vision. Here we describe how we used our new computer code, STRAUSS, to convert data into sound for the show. We also discuss the lessons learnt during the design of the show, including how it was imperative to obtain a range of diverse perspectives from scientists, a composer and representatives of the blind and vision impaired community.Comment: Published in Astronomy and Geophysics, Volume 63, Issue 2, Pages 2.38-2.40. This is the authors' accepted version of the manuscript. Visit https://www.audiouniverse.org for audio-visual resources. Our new sonification code, STRAUSS, is available at: https://github.com/james-trayford/strauss. Article is 5 pages with 3 figure

Analog MAP decoder for (8,4) hamming code in subthreshold CMOS

Journal ArticleAn all-MOS analog tail-biting MAP decoder is presented for an (8,4) Hamming code. The decoder implements a probability propagation algorithm using subthreshold CMOS networks. Physical results verify the expected behavior of the decoder and demonstrate robustness of analog decoding circuits