Meteorological microseisms and stratospheric warmings

Summary The meteorological microseisms recorded at Prague are found to be essentially independent of the occurrence of the major midwinter stratospheric warmings. This finding contributes to studying the downward propagation mechanism of some extraterrestrial influences.     

The relation between the heat flow field and the distribution ofP n -wave velocities for the European continent

Summary The dependence of P_n-wave velocities on the heat flow, temperature at the crustmantle boundary and the thickness of the Earth's crust in Europe was investigated in relation to the problem of lateral inhomogeneities in the upper mantle. A map was constructed of the distribution of P_n-wave velocities on the territory of Europe. The relations these investigations yielded, were compared with the results of laboratory experiments and all the results are discussed from the physical point of view. The conclusion drawn is that that temperature and pressure effect provide a sufficient explanation of the observed regional changes of P_n-wave velocities for the European continent.

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auum ¶rt;auu mu n¶rt; ¶rt; nmu uua (P_n) u mn nm, mnam a nmu amuu u m a mumuu n a u¶rt;aa u numa ¶rt;¶rt;m amuu. mumuu n a maa a uu m P_n- a nmu uua. u¶rt;u umam ¶rt;a mama aam u¶rt;au uuu m n¶rt; amuu u u ¶rt;au u mnam mmmm mama n¶rt;aa am. ¶rt;a ¶rt;, m ua uu m P_n- a n mum ¶rt;mam um uuu mnam u ¶rt;au a nmu uua.

     

Thermally driven hydromagnetic instabilities in a non-constantly stratified layer

Summary The convection in a rapidly rotating electrically conducting, fluid horizontal layer of non-constant stratification, permeated by an inhomogeneous magnetic field, is studied. In this connection, a temperature model of the layer is constructed, which creates a structure such that part of the layer is unstably and a part stably stratified. The results obtained are applied to the conditions in the fluid Earth's core.

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¶rt;m u m aa mn¶rt; u¶rt;uma , m um nm mamuuau u a¶rt;um ¶rt;¶rt; aum n. uaa nu m mna ¶rt; nu¶rt;um uu ma mm, nu m am mamuuum mau, a am — mau. mam unm ¶rt; aaua n, nu¶rt;u u¶rt; ¶rt; u.

     

Behaviour of quartz gravity meters under high frequency vertical motion

Summary Tests on the vertical vibrating table in the frequency range of70–110 Hz indicate that quartz gravity meters are10–100 times more sensitive at some frequencies than under low-frequency excitation. At high frequencies, the reading beam is at rest and deflected from the correct position. Slow fluctuations of amplitude and frequency near resonance could cause slow irregular motion of the beam with absence of low-frequency ground motion of sufficient intensity.

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unmauaum a mua um¶rt; ¶rt;uana amm 70–110u mam, m a m ammaaum 10–100 a mum nu uamm au. u amm au u a¶rt;um n m mu m nu. ¶rt; auauu anum¶rt; u amm au uu aa m am uamm u ua ¶rt;a mmmm uamm au n ¶rt;mam umumu.

     

Die Ausgleichung und Genauigkeit Eines Polygonzuges mit Lagengemäss Ungenauen Anschlusspunkten

Summary In adjusting a bilaterally connected polygonal traverse, whether to positionally accurate or inaccurate points of departure, the mean errors are the problem of primary importance. Hitherto, the mean errors of lengths and angles were chosen; the procedure was such that the weights of both quantities were determined from the mean errors chosen, and this fixed the ratio of the mean errors. This ratio did not change as a result of the adjustment, but the absolute values of the mean errors did. Provided the adjustment was carried out on a polygonal traverse with fixed points of departure, this change did not matter. In the case of ellipses of errors in the points of departure, this change is not permissible, because it would include the change of the semi-axes of the ellipses of errors and, therefore, also of the positional rigidity of the points of departure. The contribution of this paper is in the exact method by which it is possible to compute a coefficientc, pertaining to the mean angular error selected (in the case of positionally inaccurate pointsd), which determines the mean errorm=±e √s (orm=±d √s) of the lengthss. The solution is based on the definition of the mean error of a unit weight founded on the work of deformation. In the calculus of observations, the work of deformation has so far been determined as the deformation work of internal forces from the corrections of the individual quantities after the adjustment is concluded. However, it is possible, as was demonstrated in this paper, to express it as the deformation work of external forces, which act during the adjustment in pointO (Fig. 1) on the auxiliary static system in the shape of a console, and which provide it with the necessary deformation. If the external forces are expressed by means of the tensor of the auxiliary system, the equation for the mean error of the unit weight will provide a relation between this error and the coefficientc, ord. If the mean angular error is selected and if its weight is put equal to one, an equation of the fourth degree is obtained in terms ofc (ord), from which it is possible to compute this coefficient. From the external forces, necessary to produce the deformation of the auxiliary system during its adjustment, the corrections of the individual elements of this system may be determined. If we want to determine the ellipse of errors in one of the polygonal points, it is necessary to investigated the shifts of this point, which occur if the point is acted upon by a unit force first in one and then in another direction, perpendicular to the first. Both shifts represent conjugate radii of the deformation ellipse. From this ellipse we proceed to the ellipse of errors. The general solution is supplemented by a numerical example of adjusting a polygonal traverse with positionally inaccurate points and, for sake of comparison, also by the adjustment of this traverse with positionally accurate points.

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Anschrift: Husova 5, Praha 1-Staré Město     

Kinetic,equilibrium and thermodynamic studies of thiamethoxam adsorption by multi-walled carbon nanotubes

Because of their high adsorption capacity, carbon nanotubes have caught the attention of the scientific community and a number of experimental results confirmed their ability to adsorb many toxins from water. The aim of this work was to study the kinetics, equilibrium and thermodynamics of thiamethoxam adsorption by multi-walled carbon nanotubes in aqueous solutions. To further elucidate the influence of nanotube structure on the adsorption mechanism, the experiments were performed on both fresh (pristine) and nitric acid-modified multi-walled carbon nanotubes. The results of the kinetic studies were analyzed using three kinetic models, while the adsorption equilibrium was tested against four different adsorption models. Based on the results, and the physico-chemical properties of the adsorbent and adsorbate, it is proposed that the dominant mechanism for thiamethoxam molecules attaching to multi-walled carbon nanotubes is caused by aromatic π–π interactions (electron donor–acceptor interactions). The results of thermodynamic calculations based on the adsorption data indicate the exothermic nature of the process, regardless of the carbon nanotube type used. The decrease in entropy and the consequent negative change in Gibbs free energy, as expected, confirm the spontaneity of thiamethoxam adsorption on both pristine and functionalized multi-walled carbon nanotubes.