2,356 research outputs found
Novelty detection in video surveillance using hierarchical neural networks
Abstract. A hierarchical self-organising neural network is described for the detection of unusual pedestrian behaviour in video-based surveillance systems. The system is trained on a normal data set, with no prior information about the
scene under surveillance, thereby requiring minimal user input. Nodes use a trace activation rule and feedforward connections, modified so that higher layer nodes are sensitive to trajectory segments traced across the previous layer. Top layer nodes have binary lateral connections and corresponding “novelty accumulator” nodes. Lateral connections are set between co-occurring nodes, generating a signal to prevent accumulation of the novelty measure along normal sequences. In abnormal sequences the novelty accumulator nodes are allowed to increase their activity, generating an alarm state
The Distribution of Atomic Hydrogen Around Two Irregular Galaxies
We present radio interferometric observations of two irregular galaxies that
were candidates for having unusually extended HI emission. The galaxies, UGC
199 and DDO 26, otherwise appeared to be normal, low-luminosity systems with
modest star-formation rates. To a detection limit of 2--3E19 /cm^2 at a
resolution of about 50", however, the HI around neither galaxy is unusually
extended compared to other irregulars. The HI around UGC 199 appears as a
regular, symmetric distribution with regular rotation and a maximum rotation
speed of about 80 km/s. By contrast, the HI around DDO 26 shows a concentration
into two blobs with an arm in the outer parts to the northwest and some
additional emission to the northwest of that. The kinematical major axis is
approximately 75 deg from the HI and optical morphological axis which is
unusual for Im galaxies. In addition the velocity field in the outer parts of
the galaxy is messy and the velocity profiles at the two HI peaks are broad. We
suggest that DDO 26 has been perturbed externally or may be two dwarfs in the
process of merging.Comment: To be published in AJ, May 200
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Cavity and Microwave Experiments on Electron Plasma
A new technique for rapidly generating a sequence of target plasmas in a Penning-Malmberg trap is presented and applied in the first demonstration of cavity-resonant cooling in a plasma. This ``reservoir'' technique further enables the in situ magnetic field to be measured to high precision by microwave ECR spectroscopy. A precision antihydrogen gravity experiment being constructed at CERN will rely on this method, as there is no other method with comparable absolute, spatial, and temporal resolution which can be implemented in the Penning-Malmberg trap. These cavity and microwave measurements require accessing new regimes with the plasma parallel energy analyzer, to which end the sensitivity of the latter technique has been increased twenty-fold
Slow dynamics in cylindrically confined colloidal suspensions
We study bidisperse colloidal suspensions confined within glass
microcapillary tubes to model the glass transition in confined cylindrical
geometries. We use high speed three-dimensional confocal microscopy to observe
particle motions for a wide range of volume fractions and tube radii. Holding
volume fraction constant, we find that particles move slower in thinner tubes.
The tube walls induce a gradient in particle mobility: particles move
substantially slower near the walls. This suggests that the confinement-induced
glassiness may be due to an interfacial effect.Comment: Submitted to AIP conference proceedings for "Slow Dynamics in Complex
Systems" (Sendai, Japan, Dec. 2012
State of the States 2005
Summarizes major state policy developments in 2004 and projects likely trends for 2005. Includes health care, education, homeland security, tax and budget policy, the same-sex marriage controversy, and profiles of governors elected in November 2004
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