Estimation of per cent polarization in deep oceanic water

An isotropic model is used to describe and estimate the % polarization in a horizontal direction in the ocean at near-asymptotic depth. It is found that when the radiance distribution is described by a fourth power ellipse the % polarization = ε2, where ε is the eccentricity of the ellipse

Observed and computed path radiance in the underwater light field

This paper presents experimental data on changes in underwater radiance in zenith and nadir directions as a function of depth for both overcast and clear sunny lighting conditions at the surface. The equation developed by Preisendorfer (1957) to describe path radiance along any path is then used to predict observed changes, and predicted results are compared with the observed data

Applications of calculus of variations to trajectory analysis Annual report for 1965

Application of variational calculus to trajectory analysis of multistage vehicl

Scattering properties of Venus' surface

Radar backscatter functions Sigma-(carat)(sub 0)(phi) for incidence angles between 0 less than or equal to phi less than or equal to 4-10 deg were derived from Magellan altimetry radar echoes. The procedure includes constrained solution of a system of simultaneous equations for which the echo-spectrum and echo time profile are inputs. A practical and workable set of constraints was applied; optimization and improved results are expected as the analysis matures. The scattering functions yield information on small-scale surface structures (tens of centimeters to tens of meters) but averaged over hundreds of sq km. RMS surface slopes derived from fits of analytic functions to the Sigma-(carat)(sub 0)(phi) results were converted to map form and show patterns similar to those reported using other techniques. While all three forms are found on Venus, fit residuals imply that an exponential scattering function matches data better than either the Hagfors or Gaussian form in most areas, although the Hagfors function may be a better descriptor at some sites. Limited study of image data indicates that average backscatter cross section, and possibly its slope, can be derived at oblique angles (17 deg less than or equal to phi less than or equal to 45 deg). Offsets of the echo peak in altimetry spectra are surprisingly common and are loosely correlated with Venus topography, but no cause for this phenomenon was identified

Fast algorithm for detecting community structure in networks

It has been found that many networks display community structure -- groups of vertices within which connections are dense but between which they are sparser -- and highly sensitive computer algorithms have in recent years been developed for detecting such structure. These algorithms however are computationally demanding, which limits their application to small networks. Here we describe a new algorithm which gives excellent results when tested on both computer-generated and real-world networks and is much faster, typically thousands of times faster than previous algorithms. We give several example applications, including one to a collaboration network of more than 50000 physicists.Comment: 5 pages, 4 figure