Unsupervised seismic facies analysis provides an effective way to estimate reservoir properties by combining different seismic attributes through pattern recognition algorithms. However, without consistent geological information, parameters such as the number of facies and even the input seismic attributes are usually chosen in an empirical way. In this context, we propose two new semiautomatic alternative methods. In the first one, we use the clustering of the Kohonen self-organizing maps ͑SOMs͒ as a new way to build seismic facies maps and to estimate the number of seismic facies. In the second method, we use wavelet transforms to identify seismic trace singularities in each geologically oriented segment, and then we build the seismic facies map using the clustering of the SOM. We tested both methods using synthetic and real seismic data from the Namorado deepwater giant oilfield in Campos Basin, offshore Brazil. The results confirm that we can estimate the appropriate number of seismic facies through the clustering of the SOM. We also showed that we can improve the seismic facies analysis by using trace singularities detected by the wavelet transform technique. This workflow presents the advantage of being less sensitive to horizon interpretation errors, thus resulting in an improved seismic facies analysis.

The electronic structure of Mg 2 Ti 2 B 2 O 8 , a warwickite with Mg in the outer octahedra, Ti in the inner ones, is studied with approximate molecular orbital calculations. A chemical construction of the band structure, density of states, and bonding of this material begins with molecular octahedral and bioctahedral models and then proceeds through a onedimensional ribbon to the full three-dimensional solid. There is weak Ti-Ti interaction in this material, both direct and through bridging oxygens. Warwickite is very much onedimensional, such interaction as there is being confined to the ribbons.

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a b s t r a c tThe magnetic order of a low-temperature dimerized phase of Fe 3 O 2 BO 3 is investigated through a density functional approach which considers full non-collinear spin-spin interactions, focusing on the 15 K crystalline structure. It is found that Fe spins in the (Fe-Fe) 5 þ dimer, formed during the room temperature structural change of Fe 3 O 2 BO 3 , are parallel and have little freedom to rotate under interaction with neighbor Fe atoms. While the Fe dimer behaves as a heavy single magnetic unit the spin magnetic moment of the third Fe 3 þ atom of the Fe triad has, on the contrary, much more freedom to rotate. This is responsible for a canted spin ordering, revealed by a rotation of $ 801 of the trivalent Fe spin relative to the spin orientation of the dimer, due to spin-spin interaction with divalent Fe atoms outside the triad. Canting is thus seen to be responsible for the very low net magnetization, experimentally observed in this compound (T o 40 K).

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In recent years, 3D volumetric attributes have gained wide acceptance by seismic interpreters. The early introduction of the single-trace complex trace attribute was quickly followed by seismic sequence attribute mapping workflows. Three-dimensional geometric attributes such as coherence and curvature are also widely used. Most of these attributes correspond to very simple, easy-to-understand measures of a waveform or surface morphology. However, not all geologic features can be so easily quantified. For this reason, simple statistical measures of the seismic waveform such as rms amplitude and texture analysis techniques prove to be quite valuable in delineating more chaotic stratigraphy. In this paper, we coupled structure-oriented texture analysis based on the gray-level co-occurrence matrix with self-organizing maps clustering technology and applied it to classify seismic textures. By this way, we expect that our workflow should be more sensitive to lateral changes, rather than vertical changes, in reflectivity. We applied the methodology to a remote sensing image and to a 3D seismic survey acquired over Osage County, Oklahoma, USA. Our results indicate that our method can be used to delineate meandering channels as well as to characterize chert reservoirs.

Helicopter classification capability is a desirable feature on air defense radars, as a way of distinguishing friends of foes. However, it is still a challenging task for any radar system. The classical method for helicopter classification is the L/N-quotient method, where two signal features are measured: time between peaks and blade tip velocity. Unfortunately, these features are difficult to measure on actual target echoes with high noise levels. This paper shows the difficulties for measuring these features and presents a way of measuring time between peaks using Continuous Wavelet Transform (CWT).