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This paper shows a complete seismic-event classification and monitoring system that has been developed based on the seismicity observed during three summer Antarctic surveys at the Deception Island Volcano, Antarctica. The system is based on the state of the art in hidden Markov modeling (HMM) techniques successfully applied to other scenarios. A database that contains a representative set of different seismic events including volcano-tectonic earthquakes, long period (LP) events, volcanic tremor, and hybrid events that were recorded during the 1994-1995 and 1995-1996 seismic surveys was collected for training and testing. Simple left-to-right HMMs and multivariate Gaussian probability density functions with a diagonal covariance matrix were used. The feature vector consists of the log-energies of a filter bank that consists of 16 triangular weighting functions that were uniformly spaced between 0 and 20 Hz and the first-and second-order derivatives. The system is suitable to operate in real time, and its accuracy for this task is about 90%. On the other hand, when the system was tested with a different data set including mainly LP events that were registered during several seismic swarms during the 2001-2002 field survey, more than 95% of the recognized events were marked by the recognition system. Index Terms--Deception Island, hidden Markov modeling (HMM), seismic-event classification, volcano monitoring.

A study of discrete cosine transforms (DCT's) results in the formation of eight types of DCT's for a complete orthonormal eigenvector set. A general form of matrices creates the eigenvectors. Each DCT consists of a class of stationary processes to define suitable asymptotic behavior of the corresponding DCT. With all finite order Markov processes, all of the eight types of DCT's have asymptotical optimality.

The generating matrices of eight different versions of the discrete sine transform were obtained as generalized matrices. The latter, which may be reduced to the sum of a Toeplitz symmetric matrix and a Hankel or close-to-Hankel matrix, may be used to prove that discrete sine transforms with block length N are 'asymptotically optimal for any finite order' stationary process.

Three impression materials, Impregum, Permadyne, and Reprosil, were tested with three restorative materials, Lodestar, Dispersalloy, and Concise. Polished cylindrical samples of each restorative material with and without a collar design were used tot impression retention testing. A pullout test using an Instron machine was used to test the samples that were individually submerged in the impression materials until set. Results show similar behavior for Lodestar and Dispersalloy with and without a collar. Permadyne and Impregum were significantly more retentive with resin composite than was Reprosil. Resin composite was significantly more retentive than the metals. Impression materials may bond with restorative materials, significantly increasing resistance to impression removal. [ABSTRACT FROM AUTHOR]