Rheological modelling of measuring systems of quartz gravity meters

Summary Some phenomena, recorded during pressure tests of quartz gravity meters, are studied theoretically using a model of the visco-elastic continuum. Expressions, describing the response of the measuring system as a function of the time variation of pressure disturbances, are derived by solving the appropriate rheological equations.

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Rock mass mechanical characteristics in an opencut at bor copper mine

SummaryRock Mass Mechanical Characteristics in an Opencut at Bor Copper Mine Preliminary testing for the design of the new opencut, which will go to a depth of about 300 m, included testing rock mechanical characteristics. The character of the preliminary testing demanded by an engineering undertaking of this scale and the fundamental structural and physical properties of rock masses (fissuring, anisotropy, heterogeneity, natural stresses) are discussed and it is emphatically concluded that priority should go to in situ testing. Results are presented of determinations of the velocity of propagation of longitudinal elastic waves, elasticity modulus, coefficient of damage and shear strength parameters.With 7 Figures     

Winter anomaly observations at the Panská Ves Observatory (Czechoslovakia), 1971–1973

Summary The results of the winter anomaly observations at the Panská Ves Observatory on 2775 kHz and 2614 kHz (A3 method, f_eq1 and 0.8 MHz) are studied for the winters of 1971/72 and 1972/73. Ionospheric responses to minor (1972) and major stratospheric warmings are found to be different and relatively small. A regular winter-anomaly background absorption increase with a maximum in January was observed during both winters studied. Magnetic storms are found to play an insignificant, if any, role in the winter-anomaly phenomenon. The relation between magnetic activity and ionospheric absorption seems to be better in non-anomalous periods.     

The origin of framboidal pyrite as a surface effect of sulphur grains

Framboidal pyrite has been prepared by precipitation of oxyhydroxides of iron, peptized by humic acids using a solution of Na-sulphate or hydrogen sulphide, spherical grains of elemental sulphur being present. By peptization of iron oxyhydroxides using humic acids, a stable negatively charged colloidal system arises. At room temperature and a pressure of 1 atm., and at pH widely ranging between 6.5–7.5, sulphidation of this colloidal system gives rise to a monodispersive sulphidic sol whose stability depends on the concentration of iron in the solution, the amount of humic acids and the presence of electrolytes. In the presence of spherical grains of sulphur, arising by rapid oxidation (acidification) of Na₂S solution or a saturated solution of hydrogen sulphide, particles of the sulphidic sol precipitate on their surface and the grains become gradually replaced by sulphides of iron. At the same time, framboids of an average diameter of 14 μm are generated.     

Partial derivatives of travel-time curves of reflected waves in a layered medium

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Three-component spectral analysis of geomagnetic pulsations

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Reflection and transmission coefficients for transition layers

Summary Formulae are derived for the reflection and transmission coeficients of plane elastic waves for a transition layer. Haskell's technique and the so-called delta matrices[5, 7] are used for this purpose. No problems are encountered in deriving the reflections and transmission coefficients from Haskell's matrices[3]. However, in some cases Haskell's matrices do not guarantee the accuracy required. For this reason attention is mainly devoted to deriving the reflection and transmission coefficients from the delta matrices. In deriving the transmission coefficients use is made of the fact that some3×3 subdeterminants of the delta matrices are squares of the3×3 subdeterminants of Haskell's matrices.