Information-theoretic framework for unsupervised activity classification

This article presents a mathematical framework based on information theory to compare multivariate sensory streams. Central to this approach is the notion of configuration: a set of distances between information sources, statistically evaluated for a given time span. As information distances capture simultaneously effects of physical closeness, intermodality, functional relationship and external couplings, a configuration can be interpreted as a signature for specific patterns of activity. This provides ways for comparing activity sequences by viewing them as points in an activity space. Results of experiments with an autonomous robot illustrate how this framework can be used to perform unsupervised activity classification.     

The Colloquio Internazionale Sulla Scienza Della Fotografiaturin, 23–28 September 1963

Several derivatives of 7, 8-dihydroxybenzopyrylium chloride and of 7, 8-dihydroxycoumarin (daphne- tin) were synthesized and investigated as developing agents. They function best in the pH range 10-11, and possess similar photographic properties to pyrogallol, but show better keeping properties in solution. The best compounds are daphnetin, its 3-methyl derivative and its 3, 4-dimethyl derivative. These give higher speed for the same contrast than do catechol or metol.     

Fabrication of ferroelectric lead bismuth tantalate nanoparticles by colloid emulsion route

Abstract

Ferroelectric lead bismuth tantalate (PbBi₂Ta₂O₉ nanoparticles were successfully synthesised using a colloid-emulsion process. Monophasic PbBi₂Ta₂O₉ was obtained through calcining the precursor powder at 750°C for 2 h. The precursor powders are soft agglomerates with nanosized primary particles. After calcination at 750°C, the average primary particle size is about 40 nm and the shape of the particle is near spherical. A rise in calcination temperature results in an increase in the particle size as well as the crystallinity. The collid emulsion technique as developed was found to be superior to the conventional solid state method for preparing PbBi₂Ta₂O₉ powder with finer particles and a narrow size distribution.     

High Speed Shutters

The principles of single-shot high speed shutters are outlined including (lash, capping, electro-optic (Faraday and Kerr Cell) and image tube techniques. The limitations of transmission and response time are compared.     

Photographic Procedure for Complex Chart Visual Interpretation Records*

Comparison of complicated chart records is not an easy task, even if great trouble is taken to produce transparent film copies dye-toned to contrasting colours. The lines may cross and re-cross so frequently that the sequence of events is difficult to see. In suchcases superimposition of above-the-line and below-the-line silhouettes is helpful, since it permits both the sign and the magnitude of the error at any point to be readily seen. Photographic procedures are described for making such silhouettes from commercially available materials.     

Pitting corrosion resistance of as welded and thermally aged nitrogen containing type 316 stainless steel weld metal

Abstract

Type 316 stainless steel weld metal with 0·07%N, prepared using nitrogen bearing 316 stainless steel filler wire by the manual metal arc (MMA) welding process, was evaluated for the microstructural changes and pitting corrosion resistance in as welded and aged (at both 1023 and 1123 K for 0·5, 1, 10, and 100 h) conditions. The initial delta ferrite content was about 5·5 ferrite number, which transformed from 70 to 100% as secondary precipitates depending on the aging conditions. Electrochemical potentiokinetic reactivation studies did not show any reactivation peak indicating the absence of Cr depleted zones. Pitting corrosion studies in a medium of 0·5M NaCl + 0·5M H₂ SO₄ (acidic chloride) by the potentiodynamic anodic polarisation method showed a significant variation in the pitting resistance which depended on the aging conditions. The pitting corrosion resistance has been correlated to the precipitation kinetics of the secondary phases such as sigma, carbide, and Cr₂ N in the weld metal.