Tidal deformations of viscoelastic body

Summary The tidal deformations of a viscoelastic body are studied using the simple Kelvin-Voigt model. Expressions for the phase lag and amplitude change of the displacement vector are derived. The energy dissipation rate is calculated for the main disturbing bodies and for diurnal and semidiurnal tidal waves.

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Trends in planetary wave activity in the upper middle atmosphere inferred from the nighttime LF radio wave absorption measurements

Summary The nighttime LF radio wave absorption in the lower ionosphere measured at two frequencies in central Europe over 1963–1985 is used to infer planetary wave activity and its long-term trend in the upper middle atmosphere (∼90–100 km). The observed positive trend is roughly consistent with results based on daytime absorption. Nighttime results are less pronounced and less statistically significant probably due to perturbing effects of geomagnetic activity. The observed trends, which are probably of anthropogenic origin, are together with the daytime results [3,4] the first evidence of long-term trends in planetary wave activity in the upper middle atmosphere.     

Upward continuation of potential fields from a polyhedral surface1

An equivalent source procedure is derived for upward continuation of unevenly spaced gravity and magnetic data. The dipole layer is placed on a topographic relief approximated by a polyhedral surface, the stations being the vertices of the triangular faces. The dipoles have linear magnitudes, being directed along the normal vector over each triangle. The unknown values of the dipole magnitudes at each station are obtained by a suitable modification of the usual integral equation considering the discontinuity of the normal vector at each vertex of the dipole surface. Profile data processing is also studied. A numerical test outlines the accuracy and the limitations of the model for the case of a magnetic field significantly perturbed by a rough topographic relief.     

Line integrals of potential field data1

Information on the mass and the spatial location of an arbitrary source body can be obtained by performing suitable integrations of 3D gravity and magnetic data along an infinite straight line. No assumptions on the density/magnetization distribution or the shape and location of the source are required. For an oblique borehole, a relationship between the lower limit of the source mass and the distance to the body is obtained. The mass contrast and the magnetic moment of the source can also be estimated. For a vertical borehole, both gravity and vertical magnetic component anomalies have equal areas to the left and right of the depth axis. The particular case of a horizontal gallery not intersecting the body is also studied. If the source is intersected, a lower limit is estimated for the maximum thickness of the body along the gallery. Information on the vertical coordinate of the centre of mass of the source can also be obtained. Numerical tests with synthetic gravity data support the theoretical results.     

The photoelectron spectra of some Tl-Sb sulphosalts

The results of X-ray induced photoelectron spectroscopy (XPS) experiments on several phases of the ternary system Tl-Sb-S are reported. The binding energies of the inner S, Sb and Tl electrons increase with increasing quantities of Sb and decreasing amounts of Tl in these compounds. This is explained by the influences of the proportions of the bonded metals on the effective electron affinity of S. The higher proportions of the more electronegative element bonded to S cause the increase of its effective electron affinity. The results for Tl₂S (carlinite), Tl₃SbS₃, TlSbS₂ (weissbergite), TlAsS₂ (lorandite) and Sb₂S₃ (antimonite) can be interpreted in this way. The results for Tl₄S₃ suggest a predominantly covalent character of bonding for both Tl(III) and Tl(I), which are present in this sulfide. From comparison with Tl₃SbS₄ it could be supposed that Tl(III)-S bond has a more covalent character than Sb(V)-S bond. The results for Tl₃SbS₄ are in agreement with crystal structure data and the results of Moessbauer spectroscopy. For AsS (realgar) the binding energies of the inner electrons of As and S significantly increase, showing that the electrons in molecular orbitals are less strongly bonded to individual atoms, as compared to pure elements. The results for the amorphous TlSb₅S₈ (corresponding in composition to parapierrotite) suggest that in amorphous compound the Tl-S bonding is stronger and the coordination of Tl more regular than in a crystalline one.     

Modelling magnetization processes in single-and multi-domain rock samples using the preisach diagram

Summary The paper presents the results of identifying a model of the Preisach type for haematite grains of the single-domain as well as multi-domain size. Due to the phenomenological conception of the model, the relations between the parameters of the model and actual parameters are very complex, however, impressive accuracy and stability of the modified model indicate the need to resume studies of this problem. The model parameters also confirm the adequate properties of the vibrating-sample magnetometr (VSM) used and developed in our laboratories.