Cooling of a coronal flare loop through radiation and conduction

A simple method is proposed for a computation of the cooling of coronal flare loops by radiation and conduction, for various temperatures, densities, and lengths of the loops. The relative importance of conductive and radiative losses is briefly discussed.     

The thermal field of the lithosphere in the region of mid-ocean ridges modelled on the basis of known surface temperature and heat flows

Summary The possibility of solving the stationary heat equation with the convective term is demonstrated in the case that the velocity field of the continuum, and the temperature and heat flow on the Earth's surface are known, and that an assumption is made about the magnitude of heat flows on another part of the boundary of the two-dimensional region being investigated, whereas no boundary condition is imposed on the remainder of the region's boundary. The problem has been solved numerically for a kinematic model of the lithosphere in the region of mid-ocean ridges, based on the assumption of a broad deflected convective flow moving at a distance of more than about 150 km from the ridge modelled as a plate.

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aaa m u maua au na mna a, ¶rt;a um n m mua u a nmu u um mnama u mn nm. a ¶rt; amuau aamua ¶rt; amu ¶rt;um n¶rt;nu uu mn nma a a ma amuau a u a¶rt;a. ma na a u m¶rt; a ¶rt; uamu ¶rt;u um amu ¶rt;u-auu m, a a n¶rt;mauu u ma mu nma a amu m ma nau 150 ¶rt;u auma nm.

     

Wave propagation in physical models of micromorphic media

Summary The propagation of seismic waves in a micromorphic body, which is supposed to be one of the possible models of the medium in the earthquake focus, is studied by means of the two-dimensional ultrasonic model technique. The results obtained indicate that such a medium is characterized by distinct elastic anisotropy and by increased attenuation. The propagation velocity of longitudinal waves decreases and their amplitudes change considerably. The prevailing frequency of the waves passing through the micromorphic medium tends smoothly to one value which depends on the space distribution, orientation and dimensions of the elements characterizing such a medium. The obtained results are confronted with the theory of a micromorphic medium.

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anmau uu u ¶rt;, n muu ¶rt; u ¶rt; ¶rt; a mu, uam nm ¶rt; ma ¶rt;uau. mam naam, m maa ¶rt;a muam n aumnu u n nu. m anmau n¶rt;u n¶rt; nuam, u anum¶rt; m. a¶rt;aa amma , n¶rt;u u ¶rt;, na mum ¶rt; uu, ma aa nmam an¶rt;u, anam u aau ¶rt;m, n¶rt;u m ¶rt;. mam auam mu u ¶rt;.

     

Precession-nutation torque in terms of the stokes constants

um nu-mau m nuuau u auumu m nm ma u. m mu u¶rt;uu¶rt;a m ma nuua u uu.     

Theoretical estimation of the earth's and moon's tidal decelerations

Summary On the basis of the conservation of the Earth-Moon angular momentum, the period of the Earth's resonance rotation and Moon's revolution and the relation between tidal deceleration of the Earth's rotation and of the Moon's mean motion are derived theoretically. The comparison of the theoretical relation with the observed values indicates that a mechanism should exist which decreases the maximum principal moment of the Earth's inertia bydC/dt=–3.2×10²⁹ kg· . m² cy^–1.

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¶rt; u au ma uma ¶rt;uu um -a, ¶rt;am mmuu ¶rt; a nu¶rt;a au u u uma ¶rt;uu u mu nuu u mu au u u ¶rt; ¶rt;uu . aua mmu mu a¶rt;au auu, ¶rt;am au, m ¶rt; um m u aua ma uuu udC/dt=–3,2×10^{29 2} (mmu)^–1.

     

Statistical aspects of eliminating systematic effects

Summary A procedure for processing measurements subject to systematic effects is derived such that it ensures their optimum elimination in the results of the processing. It is proved that no other method of eliminating systematic effects yields better results.

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u¶rt; m¶rt; amu ¶rt;u umamuuu uuaamuu u nmua uuau mama. aa m uau ¶rt;u m¶rt; uuauu umamuu uu num u mam.

     

Do some shallow earthquakes have a tensile source component?

The laboratory tests carried out in studying shear and tensile seismogenic displacements occurring in compressed samples, led us to search for earthquakes with a tensile source component. To determine this component in the seismic focus, a special procedure based on the construction of radiation patterns of the combined shear-tensile type is introduced.The criteria for selecting the events produced by the combined source mechanism are listed, and their limitations are mentioned. From the seismic zones with good azimuthal distribution of stations in the world seismic network nine earthquakes which occurred in the 6-year period 1976–1981 were analyzed; for these events better agreement of the observed and theoretical patterns was found for the combined shear-tensile source mechanism than for the pure double-couple mechanism. However, the share of the tensile component was always, found to be relatively small, ranging from 1 to 13 percent of the shear component. The comparison of the two solutions (double-couple vs. combined shear/tensile) is based on the first onset signs statistics.The results obtained indicate that tensile fracturing does not play a substantial role in the total amount of released seismic energy; on the orther hand, it is expected to be more important in the creation and development of focal zone morphology from both the instantaneous and long-term point of view.     

Tidal evolution of the earth-sun system

Summary The tidal decrease in the Earth's heliocentric longitude generated by the Sun has been computed. It represents the increase in the length of year10^–7 s per century. The resonant angular velocity of the Earth's rotation is approximately equal to the present Earth's mean motion, however, for the model used, i.e., considering the Sun as the point-mass.

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u u zumu ¶rt;m u, a nuuau m a. ¶rt; mmmm uu ¶rt;u z¶rt;a10^–7 a mmu. a za m au u nu aa ¶rt; ¶rt;uu u, u, ¶rt;a, umam ¶rt;a ¶rt;u m a.

     

Local spatial nets derived from measurements of angles

Summary Some of the properties are discussed of local nets derived from measurements of angles by forward intersection. Their functionals and stochastic model indicate the way the effect of the initial data, of the model of determining refraction conditions can be taken into account, and the possibility of gradually obtaining the individual estimates of the coordinates of the points being determined.

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u¶rt; m ma a m, nm a auu nmam n au. a ua u mamu ¶rt;u mu m naam uu u¶rt; ¶rt;a, uu u n¶rt;u mua auu u m nmnz, m¶rt;z auau ¶rt;uam n¶rt; nm.

     

Definition of the normal gravity field including the constant part of tides

Summary One alternative of solving the problem of eliminating the effect of external masses, generating the constant part of the tidal field, from the perturbing potential is presented. The solution is founded on a new definition of the normal gravity field which contains this part of the tidal field. It is proved that two material circles in the plane of the Earth's equator, whose radii are approximately equal to the mean distances of the Moon and Sun from the Earth, can be considered as the source of this field. The new normal gravity field is first derived in the spherical approximation, which enables one to prove simply that the value of the normal gravity potential on the reference surface does not change, and that the change in the definition of the heights is insignificant. The normal gravity field for the equipotential ellipsoid is derived in the same way according to [1].

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¶rt;mam ¶rt;a amamua u ¶rt;umua n uu uu u a, au nm am nuu n, u a nmuaa. u a a n¶rt;uu a n u mmu, m m am nuu n aam. aam, m am umua m n umam a ¶rt; m nmu ama, a¶rt;u m nuuum a ¶rt;u amu u a m u. ¶rt; ¶rt; a n u mmu u nuuuu, m nm nm ¶rt;aam, m au a nmuaa u mmu a nmu m u m uu n¶rt;u m aum. ¶rt;ua n (. [1]) ¶rt; a n u mmu ¶rt; unu¶rt;a.