Amplitude Response of a LCR Gravimeter with Feedback at Periods of Microseisms and Earthquake Waves

The amplitude response of a LCR gravimeter with the SRW-E feedback was determined on a vertical vibrating platform. The ink-pen recorder was connected parallel with the digital voltmeter input to obtain an analog response of the gravimeter to the harmonic motion of the base with a peak-to-peak amplitude of 10 m and periods excited in an interval of 4 - 10 s as by the ground motion of meteorological microseisms, and in the interval 10 -100 s as by surface waves of distant strong earthquakes. In the first interval, an unexpected maximum of the amplitude response was observed with the double amplitude of apparent 6,5 Gal (6.5 × 10 _–8 m/s ² ) at a period of 4.8 s, and a baseline shift with the amplitude of–64Gal was observed at the same period. The value of this direct component cannot be separated from the effect of the Earth's gravity field. In the second interval, the amplitude response of the gravimeter displayed one expected maximum at a period of 40 s with the double amplitude of 8.1Gal. At the usual level of microseisms with a peak-to-peak amplitude of up to 2 m the fluctuation of the gravimeter on the direct baseline shifted by –4.9 Gal was estimated at 1 Gal. With typical Rayleigh surface waves with periods of 20 s and double amplitudes of up to 100 m, the fluctuation reached 67 Gal.     

Observations and interpretation of solar decameter type IIIb radio bursts

Solar decameter bursts of Type IIIb are observed with a multichannel radiometer at wavelengths around 12m. The time and frequency resolutions were 10 ms and 100 kHz. Observations on the time structure of these bursts are presented. A theoretical model which accounts for various aspects of these bursts is proposed.     

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Evaluation of pre-CHAMP gravity models `GRIM5-S1' and `GRIM5-C1' with satellite crossover altimetry

 The new GFZ/GRGS gravity field models GRIM5-S1 and GRIM5-C1, currently used as initial models for the CHAMP mission, have been compared with other recent models (JGM 3, EGM 96) for radial orbit accuracy (by means of latitude lumped coefficients) in computations on altimetry satellite orbits. The bases for accuracy judgements are multi-year averages of crossover sea height differences from Geosat and ERS 1/2 missions. This radially sensitive data is fully independent of the data used to develop these gravity models. There is good agreement between the observed differences in all of the world's oceans and projections of the same errors from the scaled covariance matrix of their harmonic geopotential coefficients. It was found that the tentative scale factor of five for the formal standard deviations of the harmonic coefficients of the new GRIM fields is justified, i.e. the accuracy estimates, provided together with the GRIM geopotential coefficients, are realistic. Received: 20 February 2001 / Accepted: 24 October 2001     

Isotopic-geochemical signs of coal and bitumen transformation in different-type ore mineralization: Communication 1. Isotopic-geochemical signs of structural transformation of coal and bitumen

Results of the study of natural organic matter (OM) represented by classes of solid and high-molecular-compounds (resin, ozokerite, asphalt, kerite, graphite, and others) are presented. They are developed as dispersed and concentrated segregations, interlayers, and independent accumulations and impregnation in the fracture-vein system and stratiform bodies. They also accompany ore mineralization. Combination of modern tic mineralogical, chemical, isotopic, infrared spectroscopic, and X-ray photoelectron spectroscopic) analytical methods provide insight into the OM transformation during oil formation and ore genesis. Variations in OM composition and properties define the concentration of ore elements and change mechanisms of their fixation (sorption, chemosorption, and reduction). Isotopic-geochemical signs of the structural transformation of Coal and bitumen allow us to elaborate a unified scale of catagenesis and metamorphism of the sapropel-and humus-type OM.     

Salt and pepper cleaning on the landsat processed images

This paper proposes an algorithm for removing the unwanted pixels from the categorized Landsat data without disturbing the features in the categorized data. Sample outputs of the smoothed data and unsmoothed data (original data) are presented.     

Phonon spectra and rigid-ion model calculations on andalusite

Polarised Raman and infrared spectra of (ir) andalusite (Al₂SiO₅) single crystals have been measured and interpreted on the basis of a rigid-ion model calculation. The Al-O bond strength is found to be about 70% ionic in character whereas the mainly covalently bound SiO₄ tetrahedra show ca. 40% ionicity. The interatomic short range forces are strongest between silicon and oxygen and rather weak around the fivefold coordinated aluminium. Thermal soft modes appear above 200°C and are correlated with a weakening of the Al-O bonds.